I can't do everything I want on a tablet - i.e. use specific software like full featured MATLAB. I don't have a particularly long commute, and I don't travel too much as student etc. so the portable uses of the tab don't make sense for me. I can do a lot of stuff on my phone already - particularly GPS since it seems that I was born without a sense of direction
Once I start work though, I'd probably get a tab for my expected 1 hour commute for browsing, reading, Facebook, Twitter etc. and the same at home if I don't feel like starting up the laptop. Doubt I'd use it for movies, music or games though...I like those on my console, TV and mp3 player. As to what type of pad I'd get - Android because I'm used to it and some of the Android tabs are cheaper than the iPad or Windows 8 tabs. Also, I'm massively dependent on Gmail, Google Calendar etc. and don't really want to make the switch, and I don't need anything as elaborate as Windows 8 would offer. All work stuff would be done on a company laptop anyway, so the tab wouldn't ever play a role there.
And if all tablets start costing the same as ultra-portable laptops - say £800+, don't think I'd be getting one! I'd just go for the Kindle or some other ebook reader.