I played in the beta for this, MMORPG is a bit misleading as this is more of a Diablo clone with MMO elements. You have open areas where you see other players (So you will see like 50 Iron Man's clumped together) then you have instances where you can play on your own or with a party.
So far I liked Ms. Marvel the best, she has fun little quips she says. But unlike Diablo you can't just start off and play with anyone you want, Heroes are random drops and are very rare to get. So you will be stuck with playing one of the starter characters till you get lucky and get who you want to actually play with. The cool part though is once you have added a Hero to your roster, you can switch characters at any time.
You can farm the instances and bosses as many times as you want for loot however, I highly suggest doing that and get a bit ahead of the leveling curve as things get much harder later in the game..some bosses have instant kill moves and are mad hard to take down unless you have a skilled party. Open world bosses are fun, just seeing tons of players wailing on someone like Venom is cool if not a bit funny as you will see multiple of the same Heroes....like said before a ton of Iron Man's at once.
Overall the game is fun but like all games of this type it gets really grindy and will take an iron will of patience to stick with. There are not as many Heroes to play as I would like, but they have said more will come in the future.
Cinco de Mayo