This is the most I'll have to say about it in a single post, and probably the last time I'll mention it.
It's really about your priorities. For me, it's the package. As much as I like OS X in its general execution, it's hobbled in terms of support, hardware resilience / reliability, choice and application versatility.
Over the course of last year, in terms of desktop hardware I've had a Mini, three CD iMacs, two Macbooks I used (These days I keep two in storage to dispatch to the parent if/when their MB breaks), four Macbook Pros and three Pros. These aren't office machines I have a hand in managing, etc. They were machines I (tried to) use on a regular basis.
I don't doubt that for many people out there, OS X is the better choice. It allows the less-skilled-with-computers to have much more confidence about what they're doing, removes the requirement for patronising IT support for many, and also makes them much more proactively productive. But - and I see a lot of it here - the self-admitted main advantage of Macs to many people seems to be effectively because they don't understand basic technical aspects of computing. Lack of knowledge or the inability to learn another OS is not, IMHO, a basis for declaring one platform conclusively better than another but rather an individual choice.
At the other end of the scale it's also probably more geek-friendly. Having UNIX underneath one of the most appealing eye candy is lets face it a geek's paradise. However although I am a geek of sorts, I'm not one to go deep into a system to change stuff just because I like doing so. Perhaps many enthusiasts forget that the primary purpose of a computer for the larger masses is to get stuff done, and not to run cool "hey, look what this can do" apps which have ultimately no real-life use or advantage. I rely on computers for my business, probably more than most and while I think that the Apple is a great computing enthusiast's computer, that doesn't always translate to getting stuff really done - for amusement or business.
My personal annual desktop spend is around twenty times what your average ‘one high-ish-end machine every three years’ guy spends, and my total IT spend covering servers, desktops and related services/software/hardware is very likely around three hundred times when compared to the same average user. I also happen to be my own IT guy - i.e. apart from initially commissioning systems and hardware/software from various VARs, I do all my own maintenance, upgrades, etc. And the more I look into Mac, the less there is from a truly IT-heavy professional perspective. Business computing on the Mac isn't really 'joined-up' once you get beyond the most basic SME level.
Support is a major failing of Apple as far as I'm concerned over Dell, my still-preferred supplier. My Mac Pros for example cannot be purchased with a contracted service which mentions a time to fix. With the Dell Precision, it comes with a next-day onsite service as standard, upgradable (which I do) to a same-day support and direct links to better-skilled techs who follows through the support more thoroughly. For me, the apparent benefit to many - as a faster alternative to waiting forever for my gear to be turned around by Applecare - of being able to make an appointment to waste my time carrying in my equipment to an Apple Store, commune at the Church of Apple and wait to get a Genius to take a look at it pales in comparison to a visit by an engineer onsite as soon as possible. If you have only experienced the lowest rung of support of manufacturers such as Dell, Apple support may seem superior to you. That however is definitely not my experience, and the fact that the Apple support pretty much begins and ends with Applecare is a major issue for me.
The hardware is another problem I have, and this extends to the current ‘Pro’ range most of all. It's built to be babied by students, ad execs, graphic designers et al - it's not built for people like me except for light home/office use. The other hardware issue is the matter of choice. I like choice. It gives me options. By going Apple, you get a severely restricted selection. That may be fine for some, but once again for someone who upgrades as frequently as I do, it's not really cutting it. The exception to the reliability rule I hope is the XServe & XServe RAID, as my new scientific computing grid is based on these systems. I don’t see any problems as they are not that different from Dell / HP equivalents and they will be kept in a controlled environment.
The usability of the OS is also an interesting comparison. Once I adapted from Windows to OS X, it was clear that it had major advantages in terms of weaning me away from the 'all windows maximised, Alt-Tab switch' working style of Windows. For me, long-term use of the Windows OS had ingrained some counterproductive multitasking practices. But what I discovered was that I could just as easily translate the way that OS X guides you to work with multiple apps back to Windows - and this is probably my biggest debt to OS X, in that it subtly changed the way I work with multiple apps making me more productive in the way I handle things onscreen. Many mention (in a somewhat broken-record mode) Expose as a productivity booster and while I take some issue with that, I'd say that it's also available under Windows as generally pretty solid third-party tools.
Apart from that fundamental point of multitasking effectiveness, the definitve advantages of OS X as a platform to run applications on are no longer so clear to me. For example I was an Applescrpt guru - and still have some chops in that respect - but Winbatch is also a powerful tool for automation in Windows, and I'm equally proficient with it. While apps are not specifically designed for use with Winbatch I can get the same things done and in some cases quick & dirty automation under Windows is actually easier than with Applescript or Automator. That is but a single example of things I don't find notably better under OS X despite others trumpeting it's apparently superior features.
OS X is very viable in a beginner environment. It is also better applicable to some hobbyist / vertical markets, such as the creative market - and indeed, for my grid. But it seems to be not for me as a desktop OS overall, that's my experience with it. It is not as flexible, as versatile, and the oft-mentioned superior reliability of OS X (at least on the Intel chip) seems to be a myth. As for the ‘no virus’ advantage I have also never, ever, picked up a virus or worm under Windows as I have 'systems common sense'.
Going away from the 'pro' side, I also have issues with OS X from a home-use standpoint. Music is an important part of my entertainment and I like to have control over my media. As easy as iTunes might be to use standalone, I find it too limiting given my multi-machine media requirements. And there are no other viable alternatives on the Mac, whereas there are at least 10 that rolls off the tongue under Windows. I returned to an all-Windows home media network for this reason: I have superior performance, control and ironically, usability using Windows-only software. Once again, if you are a very basic user taking baby steps for applications like these an all-Apple solution might be the better choice, but not for me. That and games mean that OS X has now taken a complete back seat in my home entertainment (one of the Macbook Pros does run EyeTV, which I find great for use as an impromptu VCR. In fact, that and web browsing is pretty much all that one particular MBP is used for these days, apart from fiddling with the OS & fun utilities).
You could argue "Why have a gaming PC? Just buy an XBox". The answer to that would be that an all-Windows setup actually leverages the power of the XBox to a higher degree, allowing the console to be truly part of your network - and having both gives you options in games playing. Also often the most resource-heavy, highest-tech titles comes out on PC's and I'm always equipped with run them properly. And there is no need to reboot, wrestle with VM's and maintain two operating systems to do so.
I’m taking my Vista cutover slowly as XP does everything I need for the time being. I’m also replacing rather than upgrading for the most part as I want a fully supported solution. My new main home desktop (an octo-core Dell Precision 690) shipped with Ultimate as did my replacement main transportable desktop (a US-sourced Dell XPS M1710 running a Core 2 Duo reliably and coolly at 2.5Ghz), and the portable (Sony VAIO G11 running a Core Solo, I found my performance fears with it in Vista largely unfounded for what I’ll be doing on the laptop) came preloaded with Vista Business. I still retain my Precision 490 with XP just as a hedge against compatibility problems – and indeed, there are a few issues with Vista still among the apps / utilities I use. I’ve received the Vista upgrades for my gaming desktops but have yet to apply them – I’ll do so when I buy some DirectX 10 games. My media centre will be rebuilt to fit in a cabinet, and at that time it will be upgraded to Vista Ultimate. None of my systems for work related stuff will be switched until next year.
Despite my various issues with OS X and associated hardware, it's not actually been an unpleasant experience overall. It's just (in some cases, woefully) inadequate for my overall requirements - but there are still a number of fun / useful stuff I still do on the platform.
Businesswise, I expected some issues and was at first prepared to deal with them in the interests of a more trouble free computer - but the troubles I experienced made those sacrifices ridiculous. As someone who actually uses the power of mainsteam apps (especially in my case Outlook - and Entourage is ultimately no Outlook) I felt hamstrung on the OS X platform for no good payback. And I must admit I have been surprised at how limiting OS X can be as a means to an end when compared with Windows in terms of entertainment purposes, although OS X itself is I am sure a source of entertainment for many.
I'll be keeping up to date, but the days of OS X being part of my main systems (bar the abovementioned XServe grid) is unlikely to reoccur at this stage.
