I've recently been playing some of this with the boys. I was intrigued by "free" and thought initially the boys would like it and I'd save some dosh.
It turns out I like the silly game. It is only loosely an MMO by my definition. There are dozens of servers and there is lots of instancing between zones and in "dungeons". I notice that most areas only support about 60 players.
In case you can't guess, Champion's is a superhero genre RPG. While you may instantly conjure images of Superman and Wonder Woman, the hero building system allows you to create a very wide range of useful and interesting characters. From secret agents, to cyborgs, to demons and wizards. It all fits somewhere in a comic book, right? So about anything goes.
The questing mechanic is very much "amusement park" designed with hundreds of "Missions" to complete. Zones are roughly organized by level of difficulty, but they spread them out quite a bit so you will rotate between areas. You may start in Canada, move to Westside, then back to Canada. But there are always a few options so you can pick where you want to run your missions.
Character advancement is an XP / Level system where you gain access to more powers at key levels. If you play for free, you'll be limited to their pre-built "Archtypes". But if pop for the $15 USD monthly sub, you can get access to more archtypes and the "custom build". I'd recommend starting with the archtypes just to get familiar with the game, but you'll likely feel the lure of the Custom Build before too long.
This isn't my first experience with Free 2 Play, but this has certainly been the longest. I don't think Cryptic (the developer) has done a particularly better job with their game in my case. I just don't like wow/fantasy clones. If I want fantasy, I play WoW. There isn't any reason to play anything else. But if don't want fantasy, the options are much more limited. CO is a good departure from WoW-clones even if it does use a lot of the same concepts (missions, levels, classes, etc).
The game does offer classic features like banks, auction houses, and crafting. I've dabbled with these, but not fully explored them. The end-game seems limited. Level advancement stops at 40 and after that it appears your options are 1) PvP or 2) make alts. So it remains to be seen how far Cryptic will take it. It shows a lot of promise, but still falls short of the big dogs in the MMO industry.
But for now... POW! BAM! WHAMO! Game On!