I've said on here before I love my Kindle. It doesn't replace books, simply puts them in electronic format. It's light, easy to read,and can provide you with as many books you want, and stay the same size and weight. Real handy when traveling. Right now I have about 200 books, all carried in one hand.
As far as wi-fi goes, I like it. It allows me to buy a book anywhere I am, for at least 50% off of the hard copy price. If I see a 30.00 book I want while we are out shopping, I go out and punch it up on the kindle and pay no more than 15.00. Nice. I don't feel like I'm a traitor to the world of literacy because I didn't buy the book. I read for my own entertainment and enlightenment, and especially in this economy, cheaper is better.
Allthough the initial price of an e-reader seems high, it pays for itself very quickly in savings on book prices.
My complaints are few, but there are some. #1 being that Kindle is not backlite, would really be excellent then.
#2 is no color, yet. I'm thinking about moving up to the new Nook, with color. I would probably get most of my magazine subscriptions electronically then.
All in all, I'm a true convert to electronic readers.