Simply put, I hate the user interface. Keep in mind that I'm stubborn and somewhat reluctant to change (e.g. I still use XP on my primary and work PCs, though Windows 7 Pro is installed on my laptop, only because I didn't have much luck trying to install XP on it

). Old habits die hard. I'm not a fan of Windows 7, even though I've been using it off-and-on for about a year, only because I didn't want to be caught off-guard if someone asked me a technical question related to OS management, plus it would reflect poorly on me as an IT employee.
Windows 8 though, there's nothing that I fancy; everything about the 'Metro' interface just irks me. It's not what was added, but removed feature-wise that reinforces an already weak perception of the OS to begin with.
At this point, if I wanted a tablet, I would lean towards something Android-based (as I'm a huge proponent of Google) and something Apple a distant second (only because I want something that would interact well with a Pioneer A/V receiver).
If you get a chance to play with a Microsoft tablet and love what it offers, by all means, get one because it suits your needs. I don't need a tablet at the moment, though I won't pass on the opportunity if it was priced right, just as long as it's not 8-based.