Overrated: I dunno, you all list Maplestory and WoW, but how much time have you really put in on those games? Most of you are probably just calling them overrated because you either just didn't enjoy it right off the bat, or don't have the money to put in for subscriptions/NX. I spent a long time playing Maplestory (several years, while I was still in high school) and it actually can be really fun if you put in the time, and have a good group of friends to play with. And WoW is the standard for all MMOs right now, hate you break your heart. No, I don't like WoW and I don't play it, but the fact is that Blizzard just got it right. That's why every time a big MMO comes out nowadays, articles about it tend to say, "Could it be the WoW killer?"
(I know some of you put in a good deal of time on one or both of these games. I was just generalizing.)
Underrated: DC Universe, Metal Assault, Spiral Knights
Vindictus isn't underrated, it's Nexon America's second most popular game (behind Maplestory). However, Metal Assault is a new game out by Aeria, and is very fun, but probably won't get near the userbase that it deserves, simply because it's being published by Aeria. Nothing against them, but they have a tendency to drive players away with poorly-handled events and expensive cash shop items. I would personally love if Nexon America picked up Metal Assault instead, since they would likely handle it much better, but the organization of the game is too similar to Dungeon Fighter.
And this is my warning to you, don't call people's opinions closed-minded just because they aren't the same as yours. It's pretty rude, and in this case comes off as instigation. Just be careful how you say things, alright?