I've recently purchased a tablet pc to use to read around the house so that I'm not tied to the computer. I've quite happy with it.
I just wanted to mention though as far as reading outside the home, like taking a quick read in the line at the MickeyD's or snatching a moment here and there over the course of the day - it would not be my personal choice "if" there was a dedicated device available in the size I would need (10"x<something) and reasonable pricing. As soon as one of those is out, I'll be grabbing one fast as I can.
3.5 lbs can be a lot heavier than you think too. Try to find something that's 4lbs and wave it around and see what you think.
Even being lighter than a laptop, it's still far heavier than a device, eInk is a superior delivery to the eyes and the battery charging would probably be an annoyance to anyone else. I just bought 4 adapters and plugged them in at the 4 places I was likely to read so I didn't have to haul that around the house too. But then, I'm divorced <laughs>, not an option for everyone.
Anyway, I just wanted to mention I consider my recent used tablet purchase well worth the money but I also consider it a temporary thing until they make an e-reader device I can use.