It's a nice building to look around, but nothing too exciting. If you are really into architecture or you just want to get indoors for a bit, or have nothing better to do, it's a nice little 30-min. activity. If you go to the top floors it's mostly glass everywhere so it has some cool views.
Sometimes they have different events or shows going on, so ask the staff. The facilities are pretty nice if you just want to sit and read or go online (computers available). I think you need to have a library card/register before you use the computers, or borrow books/media, of course.