I love Poznań and everything in it. I like clubs, pubs, shops, streets, busses and trams. And people of course.
There are a few places one should see when comming to Poznań. The most important would be: Ostrów Tumski (with the Cathedral in the center) and the Old Market Square.
The Old Market Square wins in numbers I guess. I don't want to write here about it's history and architecture. I refer the potential tourists to the links below:
Always helpful Wikipedia
A bit of history
I want to say why I like the area. It is always busy and there's always something going on. In warm months there are restaurants, pubs and clubs open with umbrellas outside to you can sit and enjoy the good weather. In colder months you can enter them and enjoy someting hot or strong to keep he low temperature away. There are little shops with souvenirs to visit, performances to see, architecture to admire, museums to visit, discoes to dance in and people to talk.
My favorite spots:
The Town Hall, every day at 12.00 our famos gouts appear :)
My favorite fountain - Mars