Maps need to generally be fun for everyone. It's not about how professional or good-looking your map is, but rather how fun it is.
You know your map is good when players ask for a remake at the end of the match(win or lose). That's the best way to tell if your maps will become popular, or be left in the dump. When players ask for a remake, they want to play the game again or want another chance at beating it. They want to play your map again. The phrase "re" should be praised by all you serious mappers. It tells you "this person wants to play my map again". When other players see the "re", it tells them "this map is probably good, this guy wants to play it again".
If players constantly ask for a remake, then you know your map is good.