It's not new, been out for a short while. Been playing it for the last couple of months with some friends and it is awesome. There is deffinately alot of balancing that needs to be done. For instance, if you play as Amumu, sit back and get crap loads of xp, hit a mod every now and again, you get enough gold to put your attack speed up and get life steal, you can pwn anything, and better yet, you can steal kills because of throw bandage which, with lots of sp, can kill nearly any hero in one.
Also, if you get just about any caster and whack loads of spell power on, there are some whose skills have near enough 0 cooldown time...with the right build and rune book, you can have it so you one hit anything from range, have ridiculous mp regen and never have to wait for spells to recharge, because the cooldwon is so damn fast.
It is still so so so fun though, but are they not on about making it into a full game, then it will be no longer free?