my brother is studying there, but I've only been there a couple of times personaly.
Anyhow, if you're gonna study there you're likely to have a good time. It's a very nice student town, with lots of gatherings and parties and lots of "student pubs" with cheap beer (compared to other places in Sweden, so that doesn't say much). Not to mention there's a slightly higher percentage of female students than of male dito!
If you aren't gonna study, you'll have to pay a little more for the beer, and during the summer a large portion of the student population will be elsewhere, but it's nevertheless a nice town.
Also, you could go visit the "Uppsala högar" which are the grave mounds of ancient great kings.