I've been a Tablet PC user for a little over 2 years now. My first Tablet was an Averatec C3500. I replaced that with an HP TC4200 about 7 months later and it's still my current system.
I purchased my TC4200 through HP's Business Outlet site as I didn't see a need to pay full price. They offered the same warranty coverage as a new one so I couldn't see any drawbacks. The unit has worked flawlessly for me the past 19 months.
I went with HP as I wanted a business class unit that wasn't loaded with a lot of extra junk. In addition, I wanted good support as I'm a Small Business Technology consultant and needed something I could depend on while going from client site to client site. To that end, I've broken two of my "pens" and in both cases HP support had replacements for me the next morning!
I use my Tablet for just about everything. I have a Cingular Broadband Connect Aircard for it, so I'm pretty much plugged into the 'net everywhere I go. I read my E-mail on it, surf the web, read magazines (Zinio), my books (MS Reader), and "live" in OneNote, my number one application.
With the internal battery I get about 2.5 to 3hrs of life. I have a second battery as well as the travel battery and with the three I can go about 10-11 hours without plugging in.
Last week, I installed Vista Business on it as HP finally had all the drivers available for it (although I had to grab a few from the TC4400 download site) as well as the Vista drivers for my printer (HP 7310). Cingular also has their Vista version of Communication Manager available as well.
So far, it's been working great, and I like the Vista interface on the Tablet. When I'm not using it for work, I enjoy Ink Crossword from the Enhancement Pack, Mahjong Titan, and Spider Solitaire.
About the only thing I don't use my Tablet for is music, podcasts, and videos as I use my Zune for that.
Well if I haven't put you to sleep yet, you're pretty close to it

so I'll wrap up for now.
Looking forward to participating here on the forums.