If you want the lastest fashions, perfumes, and Western-style goods, the Stary Browar is a mall converted from a former brewery in Poznan.  Even if you don't want to buy there, the structure is wonderful and won a European award for excellence in design. There are a number of good quality restaurants. It's really worth a look.  For books, Ikom is the best.  It is a huge media store about 20 min from the Square.  It also has videos and music. In the street on the east side of the Centre, there are lots of good value shoe shops