The Uppsala city library is conveniently located on the main shopping street in Uppsala (gågatan).
It can be a great place to borrow some free wifi (password is on the bulletin board). If you're just visiting Uppsala, I wouldn't go out of my way to stop here. Heads up if you're borrowing the wifi for a bit, as is typical in Uppsala, they do charge for bathrooms.
For books, it's primarily Swedish books (surprise!), but also has several shelves of English and easy Swedish books. The librarians were nice and helped me find an easy Swedish book.
As far as studying goes, it's not the best environment. There were an awful lot of of crying babies and people talking loudly on cellphones last time I was there. I guess on the other hand, it's a lot more relaxed than the "shhhh!" libraries I'm used to.
Just as a heads up, if you are looking for a beautiful library and a quiet place to study, you should hike up the hill and check out Carolina Rediviva. read more