I'm a new Mac user and Leopard is the first Mac OS I've used extensively...I've read in these forums that some people actually prefer Tiger to Leopard...could someone provide me with reasons why? So far I've experienced excellent compatability, speed, and awesome features such as stacks and spaces at my disposal.
What you have to understand is that for those of us who used Tiger, there was a long stretch where Tiger was almost hassle-free. All the bugs had been long worked out, apps had been tweaked (or in some cases premiered) to work for it, and it was an all-around consistent OS. However, all of that was due to Tiger's age. Tiger came out in April of 2005, which means that it has had over two years to be gradually perfected.
Leopard has had all of 2 months (and a few days) to be tested in the "real world." Naturally this means that problems will arise. I'm sure there will be plenty of old threads from April-June 2005 expressing rage and hatred at Tiger ("oh why didn't I stick with Panther," for example). Tis the nature of all things technologically new. Hence, an older OS can offer familiarity, consistency, and reliability.
Now, as for Leopard's features.
Time Machine: As of now, a mere extension of other programs, but important because it really makes backing up easier for those who don't seek out extras for their computers. I think Time Machine is a good idea not because it brings anything new technologically to the table, but because it will (or hopefully will) change backup habits (which are notoriously bad). However, there's nothing terribly "fantastic" about Time Machine in a "must have" sense.
Spaces: Again, an extension of other programs. However Spaces offers a similar advantage to users who don't seek out extras for their computers. It also helps those with smaller screens. Nice, but not a must for everyone.
Stacks: The most half-arsed attempt at innovation I've ever seen from Apple. Critical features are missing (ie, the ability to "Quicklook" from a stack), the interface is horribly implemented (opening a folder will merely launch a new Finder window, which is how it was before Stacks

), and without tweaking, a stack can be difficult to distinguish from other stacks (ie, they could all look like folders or documents). Now I believe one of the betas of Leopard had most of what I mentioned fixed, but for some reason it was not available in the final version for some reason. Hopefully we'll see it by .2.
Quicklook: The strongest case for Leopard. Easy to use, saves time, and has no down sides. However, if you have stability with Tiger, you certainly wouldn't waste time and money installing a potentially problematic OS for just one feature, especially one as minor as Quicklook.
Hopefully that explains why some of us prefer Tiger over Leopard (not that I do; I've had Leopard on since October and overall I'm pleased. Sure there have been problems along the way, but it hasn't been overly horrible for me).