I spent about an hour over the weekend playing the DCUO beta on my PS3, and I've also skimmed some of the information about the title available online.
The good news is that I enjoyed the game, to the point where I'm probably going to save the content for when the game actually comes out. There are some flaws; the menu controls on the PS3 controller are awkward (as always), and newbies are hit with a lot of choices up front about powers, weapons, and skills, with limited information to evaluate the choices (or determine which, if any, can be fixed later). Even so, the devs really nailed the atmosphere, and I'd rather be playing this than anything else I own on the PS3 at the moment.
On the downside, the content appears to be extremely limited; I expect to pick the game up with the included month in February and then resubscribe for a month every few content patches. Ironically, playing the game on the PS3 helps with this plan. I don't own either a keyboard or a headset, so I won't be able to communicate in any meaningful way; this greatly reduces the chances that I would make any friends and then feel compelled to stick around in a game when it's not delivering content.
I fear that PC MMO players are going to be very disappointed with this project. Compared to a single player PS3 game, though, DCUO offers more depth and more content, at a price that is only slightly higher so long as you game the subscription system appropriately. Infrequent players, and those who spend a lot of time replaying the initial content, will pay more than they would with the current console $60 + paid DLC model. If, on the other hand, you play a single character, pass on the inevitable microtransactions, and carefully time your subscriptions for when you actually have time to play, you may actually see all the content for less than it would cost to unlock DLC content one hour at a time.
In the end, I'm not sure that it's entirely a bad thing if we start to get more MMO's that aren't necessarily designed with the expectation that players will stick around for years on end. Many of the most unpleasant things about the genre result from developers trying to extend the /played time on a game beyond the legitimate entertainment value of the product. By contrast, Sony's PS3 division would like to continue to sell you new games, not merely continue to charge you for games you've already purchased. Though I'm not convinced that a monthly fee is the best approach (for either players or SOE), I'd like to think there's some potential in games that deliver a smaller quantity of higher quality content.