CoH/CoV isn't like most mmo's on the market, there's no equiptment, no loot and no tradeskills, the game is primary combat, it doesn't attract many hard core players.
I've tried to introduce players from my AO and WoW guilds in the past, most played for a couple of weeks then quit, the games not for everybody.
Me, i've been playing since beta and absolutly love it, i've played a few mmorpg's and CoH/CoV has the best combat system in my opinion, fast paced and feels more involved then other games.
CoH/CoV's equivilant to loot is enhancements, these randomly drop from mobs and you can use them to increase the effectivness of your powers, if an enhacement does drop, it's automatically put into your inventory. There's no fighting over who should get what or no slow down while you loot downed mobs.
Mobs in both games are mainly villian groups with a couple of hero groups thrown into CoV, at lower levels most mobs act the same but as you progress your introduced to different villian groups and some old villian groups pick up new abilities. My favourite group would have to the freakshow.
Also unlike most MMORPG's, i've yet to run across a damn dragon!
If you have a good spec machine and can crank the game up to high settings, the game can look quite impressive, most powers are big and flashy with a loud soundeffect to go with it, when you fire off a "nuke" power, the rest of the teams going to know about it. We did have a few screenshots in other threads but they seem to have disappeared.
Loads of other aspects of the games i could go into but i'm far too lazy.