I'm pretty sure they marketed it as a MOBA. I signed up for a key a bit ago but never got one >_< Hopefully they release it soon, I never played Dead Island, but I do like Zombies and MOBAs, so I'm eager to try it out.
It is alright but it kind of suffers a lot from World of Warcraft Syndrome... In that... League of Legends is better so to speak.
As well some characters are outright better then others in certain roles in PvE. (though that should be somewhat obvious, given that characters are designed to excel at PvP with PvE being more of an afterthought). It is kind of a shame because you get a strong sense that PVE could be a lot of fun, but the MOBA design philosophy is mostly "Slow and steady wins the race" and the PvE really needs to speed up while also throwing more at you.
One aspect of the game I really like is the fact that all characters have three versions of themselves. With each version being sort of an offshoot or reverse of the basic character. While "Armored" versions mostly stay close to the original (ok not really), the "Mutant" versions are often the most distant from the original concept.
I honestly like to think the two versions represent the sort of two paths their stories could have taken... but honestly it is more that the characters start off as basic, turn to armored, and then become mutants.