Absolutely great game, I recommend this to anyone who likes MOBA's and 2d platformers.
The art style is great in my opinion, a bit funky, a bit cartoonish and a bit futuristic.
Also the musics are pretty nice as well, especially some of the character themes and killing spree themes.
The gameplay is really nice, I think the netcode is done very well, I honestly have never saw any sort of glitch/bug/lag relating to the game, but to my own connection (which can be bad sometimes).
What I love about the game is that you unlock characters, levels (only 5 of them at the moment, 4 of them are playable on online) and skills. The characters and their skills are very unique in my opinion, and some of them are voiced by famous people (for example, TotalBiscuit voiced someone but I don't remember who).
There is a lot to do and also it includes some sort of ranking I think, I haven't played this for a while so I don't really remember how it works.
Also the updates are great, they release new characters and (very rarely) maps, and they balance the game. If you go play the un-updated PS3 or Xbox 360 version you'll see it's a lot more unbalanced than the PC version. The developers really care about the game and it's community.
I might have lost my inspiration for playing this game for now, but if you play it enough I think it'll catch you and it will be like a routine for you. When I first bought it for PS3 (didn't have a computer back then, long story I guess) I absolutely couldn't stop playing it, especially after 3 of my friends bought it and we played it online/at sleepovers, which was tons of fun.