The game is pretty much a copy of an old Warcraft 3 map Defence of the Ancients ( DotA ). HoN is an improved version of DotA. Any DotA player should recognize most of the hero pool in HoN, but the makers have been adding their own fun to play heroes, which to some extent are more unique than DotA heroes mostly because of the improved game engine.
HoN is a competetive game with a harsh community. Newcomers are often scared away because they don't understand the game enough and players who find their lack of skill disappointing, start flaming thus causing people to quit, but if you're interested enough I'm sure you will do fine.