ESFPs are pretty cool...they get me all pumped and stuff, and they appreciate when I get all deep and nerdy on them since we click all the time anyways. Don't always concentrate when they need to, but it gets to them eventually.
I'm not sure if I know any INFPs but I do have a few hunches. They make great conversation and company, that's all I know for sure.
ENTPs are crazy crazy awesome. I don't like it when they're serious, though- it's really scary. Thankfully, these are rare occasions.
ENFJs are pretty different from me. We have great fun though...occasional deadlocks of accomodation, but it's okay..