Mostly good game, but some issues that make it unacceptable as an MMO.
There are TONS of different ablities to choose from, and dispite a couple of entry level abilities that everyone has, most people will not have the exact same loadout, regardless of their chosen role (control, tank, healer, dps, etc). This makes the "action" interface much more interesting, as you have to use a combination of special abilities (buttons 1-6) and your selection of combo moves (which mostly consist of left, left, right mouse button clicks or holding various combination). It makes the combat fairly diverse.
The character customization is very nice, and I enjoyed every second of switching my character's gear, and even getting crappy gear that I didn't plan on using just because I didn't have the "style" of that type of gear. I could then change my outfit color scheme to make my hero (or villain) appear as I choose.
The voice acting is mostly done very well, and it's everywhere. All quests are given to you over a voice over comm system. NPC talk to you on quests and have very cool dialogue. And speaking of the quests... some of the quest chains are very fun, and even memorable.
So why the low score???
The environment... although fairly impressive looking... is repetitive. Painfully repetitive. I played from lvl 1-30 on multiple characters, and found that almost everything looked the same. I'm either fighting in metropolis, or Gotham. That's pretty much it. I get it. It's DC, and those are 2 major locations... but there's SOOO much more they could have done. The Trigon quest chains, for example... you go through the city fighting demons. There's little if any difference in the environment. Even when you FIGHT Trigon (well, at free Raven), it's just in some building. He has the ability to manipulate his environment to look like ANYTHING. He could have made that place look awesome... but the designers just let it take place in some stupid garage or something (and that was in an instanced area, so it could have been anything they wanted it to be). BLAND. I felt like I was on one long quest chain because the environments really never changed. I stopped playing the beta, even before it was over... because I just couldn't stand it being so repetitive.
Now I"m going to do a comparison, and I'm sure you know what I'll compare it to... WoW. But not as an overall experience. Some people don't like Warcraft's gameplay. They thing it's repetitive icon clicking (which it is to some extent). I WILL say that I find the combat system in DCUO much more enjoyable then WoW's.... but wow does one fantastic thing... they make their environments diverse, exciting, and they make them appear as if they match the situation. You FEEL like this place represents the quest chain you're playing... playing every ten levels feels different because the scenery is soooooo different. DCUO... you never get that. what building will I fight outside of next? Hmmm... who knows. Oh. these enemies are on TOP of the building. SWEEET. Oh... these are in an instance... in the building. I finally get to see what the inside of the building looks like YAY. This is an MMO. It's not a spiderman game where you fling yourself through a big city for several hours, beat the game, and be done with it.
It's really a shame, because it has everything else going for it. If DCUO somehow managed to steal the environments from World of warcraft, but change NOTHING else... I'd be playing it right now.