Every Polish city (except Gdansk) has a Rynek, or town square, which is the main place to visit. The Rynek in Wroclaw is very big, and due to restoration for the Pope's visit in 1997, very bright. Some people use the word Disney to describe it, but it's not that bad.
Outside the Rynek, about a 15 minute walk brings you to a small island and a cluster of churches called "Ostrow Tumski"...literally, Tumski Island. This is graceful and quiet place for a walk any time of year and it's here that one realizes what an image problem Poland has in the west.
Wroclaw also has a really interesting WWII history, and if you walk a little further, you can see where the Germans raised part of a residential area to make an airstrip to head back to Berlin, a day or two before their surrender. This is now a traffic cirle called Plac Grunwaldski.
Lastly, do not let your ideas about Polish food point you straight for Pizza Hut (although there is one right near Plac Grunwaldski). I never thought I would eat hot creamy cabbage or beet soup, but I do now.
Quick Tips:
Honestly, Wroclaw is not an extended destination spot like Berlin or Budapest. But both of these cities are nearby and easy to get to. Krakow is five to six hours by train and there are some great mountain towns not far from Wroclaw, both in Poland (Karpacz is my favorite) and on the Czech border. There is great skiing here, pretty much until the begining of May.
I'm trying to avoid talking about the weather, but to be fair, Spring, although lovely, comes late. English is not widely spoken in Wroclaw, but I got by with minimal Polish for two years. If you speak a little German you'll be fine.
Best Way To Get Around:
In Wroclaw, you can walk to most places of interest. The trams are great too. Always check ticket prices and stamp your ticket. Inspectors are mean and they WILL take you to the police. Sad to say, I know this for a fact. Taxis are fine, but you should call them, rather than pick one up from the cowboys who linger on sidestreets. As for getting around in Poland, trains are pleasant and efficient, but buses will take you to the smaller, less touristed areas, especially ones that are good for skiing.