bbPress vs phpBB and the rest... which is the best?

bbPress looks pretty cool. I've played around with simple machines and phpbb many times, both are nice. But, bbPress looks like it blows the two out of the water. Have you used bbPress before? If so, what's your opinion on the message board program? I'm thinking about starting up some new discussion sites, and I'm considering using the bbPress platform. If you have some feedback concerning bbPress vs phpBB or bbPress vs Simple Machines, let me know.