I'm not concerned about the quality/experience of the intel switch - I've been through the 68K->PPC switch and the OS9->OS X switch, and while neither were 'trouble-free', they also weren't that big a deal - much less trouble than switching from Win 3.1->Win95, or Win95->Win98, or from Win2000->WinXP, all of which I also did.
My concern is this:
1) I'd been planning on buying one or two new PowerMacs, one for home, and one for the office. I've now frozen my buying plans until I learn more about the product road map, and what kinds of products and price points I can expect. The Quicksilver G4/800 and the MDD dual G4/867 will just have to soldier along until I clearly understand the product/price/performance roadmap, and can make a reasonable decision about whether to buy current technology, which works fine, or wait 12+ months, and get the new architecture. Result: ~$5000 in revenue to Apple on hold.
2) Two people in my office had been looking at getting Powerbook/iBooks in the next couple months. I felt just fine about recommending that they do so, as I'm confident that a G5 Powerbook wasn't coming down the road anytime soon. With such a major change in mobile architecture, and the new Pentium-M's looking outstanding, my advice would have to be that if they don't need them urgently, they should wait. Result: ~$5000 in revenue to Apple on hold
3) Apple has largely been able to justify their hardware pricing based on their alternate architecture, and claiming that you couldn't compare Apples to Dells on a 1:1 basis for price. Given a move to essentially similar hardware, and a known retail price for OS X, charging more for identical hardware will become increasingly difficult, IMHO. While Apple will argue that in some way their 3.2Ghz Pentium-D box with 1GB of Ram, 160GB HD, etc. is different or more valuable than the one from Dell (or home-build, or whatever), that will be a very hard sell.
The distinctive architecture gave Apple some room on pricing that is going to be lost. Everyone knows what a Pentium box + an OS costs - just go to Dell and check it out. If Apple's price for the identical Pentium box + Mac OS + whatever Open Firmware chip they throw in to tie the hardware and software together is substantially higher, that's a major problem.
So, in short, I'm a big fan of the speed and capability increases that the Intel move will provide - especially on the mobile side, the PPC line is at a standstill. As a buyer, both personally and for my small business, I need a clear map of what I can expect over the next two years, otherwise I'm going to hunker down, and buy nothing at all untill that map becomes clear. I'm also going to have a very hard time paying the kinds of prices (mostly on the desktop side) that Apple has traditionally gotten for their high-end machines, if Wintel hardware is cheaper, and I know that I could run OS X there instantly if Apple would unlock it.