Regarding EVE, it has the steepest learning curve and biggest penalties ever, in any game. You can easily lose weeks, months, or years worth of gameplay(read assets/items) just from one mistake(read learning experience). But besides that fact EVE is probably the most intriguing game for mature players, there is a lot of social interaction, bonding, politics, espionage, capitalism, and world domination. Its a very complicated game that is nothing like your cookie cutter hack and slash MMORPG that you see these days. So its not for everyone.
What it all comes down to is that any MMO will be fun and enjoyable as long as you are playing with friends, or can find/make friends to play with, it doesn't matter what game it is.