The graphics are only okay. The music is one repetitive loop. While many of the champions have cool designs, the devs stoop to an almost insulting degree to make almost every single woman fanservice. I mean, am I the only one who feels condescended when a game constantly releases "hawt" female characters, thinking I'm supposed to get aroused by a bunch of textures? And the game is willing to completely ruin any sort of consistent art style just to give more fanservice.
Other than that, the champions have little persoanlity. They only have a few lines. The voice acting is good.
The gameplay is the best part, but its still not great. First of all, the early game is way too passive. You don't lose gold when you die, which means that the towers have to be buffed to absurd levels to stop rampant tower-diving. That means there's almost no tower-diving. Also, Flash is complete bullshit. Almost everyone uses it and it means every single champion has an escape. That makes the early game even more passive; why tower-die when the enemy an just flash away?
The particles lack any sort of characterization, if that makes sense. In a teamfight I have no idea which champion is activating which abilities.
It's said the game is free, and technically it is, but you are most likely going to spend money on this game. Most champions cost a ridiculous amount of in-game money. Oh, and the community is horrible but that's par for the course of any MOBA.
So overall, the game isn't very good. Just play Dota 2 when it comes out (or buy into beta). The graphics are better, the music is better, the characters have more personality, all the heroes are free, there's actually some aggression in the early game, and not every champion has a bullshit escape mechanism (just a few- looking at you, Anti-Fun). It's a bit harder to learn but not much, really. Learn to creap-stack, creep-pull, deny, block creep waves, animation cancel, and orb walk (and none of those are as hard as they sound), and you can transition to the much, much better Dota 2.