There are also books you can read, borrow and return. The book selection seemed more recent/popular, not a lot of old books (still it has 100k books). To those that comment on the how little books there are: There are several other libraries in Helsinki that house old and vast amounts of books. Helsinki has nearly 40 public libraries and numerous scholarly libraries: https://www.myhelsinki.fi/en/see-and-do/sights/helsinki%E2%8...
Overall it feels like a great place for people to go outside of their home or office to read, meet with people, take their kids to, and for free.
I uploaded a few mobile photos and videos if anyone is interested: https://www.dropbox.com/sh/z7ez8rhisktpaac/AAD7xd6xsCESP6LhJ...