I don't know anyone I've recognized as ENTJ, but I know a few ENTPs.
I think they're great. They're funny as hell and come up with some really innovative ideas. They are quite the characters, one of them sometimes just says "BORING!" if he isn't excited by something. However, if you get into a really serious discussion/debate, it can feel a little uncomfortable, too, because sometimes they seem to expect you to come up with something just so they can beat it down. They also seem to like to be able to reference as many things as possible, which is one reason why they can be a lot of fun, but it also can come off as a sign of weakness when they seem ashmed they did not know about something others seem to be fairly familiar with. One of them proudly admits they are selfish, and it actually comes off as kind of charming in a way. They can really get into one-up manship and being the best, and can be "acheivement whores" (my friend calls himself that).
Overall, I like them, and occasionally find them inspiring.