So after spending a week tied to an HP Compaq 2710p tablet running Vista Business Edition, I can say that it's actually quite usable and that overall, I've enjoyed the experience. Vista on this laptop has been relatively stable, able to handle my workload well, and though it's not as polished as Mac OS X, it's not terrible. There are more than a few things that irritate me about the OS, but it's not dog slow on this system, the sleep/wake cycles do work (most of the time) and hibernation works fairly well too. The lack of a native shell is really quite annoying to me, since I generally have a dozen xterms running at any given moment, and I really like to call them from the local system, rather than run an X server on the laptop and ship them from a Linux box, or use putty (or similar) to SSH into other systems just to get to a shell. I am running Cygwin, which mitigates this issue somewhat, but it's still not the same.
I like the gadgets, though on a laptop screen, they get covered quickly. I like the visual effects, which are smooth and attractive on this system. I like the tablet features, including the handwriting recognition which is surprisingly accurate. I was pleased to find that Firefox 3 on Vista is very fast and very stable, even when pushed very hard. If given no other choice, I could run Vista and get my work done.
However, I'm not going to be staying in Vista-land. Since I do have other choices, I still prefer Mac OS X and Linux.
The Start menu in Vista (and all other iterations) has become far too ornery for me. Navigating to new apps, or to find apps is annoying and too clumsy. The quick-launch menu in the taskbar is far too small, and even gadgets that supply a larger quick-launch facility don't really work so well since on a 1280x800 screen, it's behind all other windows most of the time. The ever-changing list of frequently-used applications in the Start menu has always been a source of wonderment to me. Occasionally, I find an app in there that I've actually used recently. The rest are just thoroughly bizarre. I've never used Windows Fax and Scan or Backup Status and Configuration, yet there they are.
While the sleep/suspend cycles do work well (better than anything I've ever experienced in Windows XP), they're still not on par with Mac OS X. Time to wake is quick, but several times the system seemed groggy, and took quite some awhile to present me with a usable interface. That said, I have yet to lose any work or have a spontaneous reboot when coming out of sleep. That's definitely a plus.