Playstation 3 - Should We Get One?

We have a Playstation 2. We're thinking of trading it in, and getting a Playstation 3. So far, the only con we can think of is that we won't be able to use our Guitar Hero 3 guitars in the new Playstation. Oh, and it's kind of expensive. Although, since our DVD player died, it might be worth the money to have an all-in-one player.