I am enjoying Champions Online.
Most of the stories I've done so far are very tongue in cheek, but that matches my sense of humor.
The costume creator is pretty robust. You can make things in it that you could never make in COX. Last night, I saw a player whose character looked like a giant insect ... in a way that you could never create in COX.
My favorite characters in COH were ELEC/ELEC melee ... a Scrapper and a Brute. In CO there is no Electric Melee, but I've been able to build a ranged toon that feels nearly as hard to kill as my Brute ever was. And the Electric Animations in CO are pretty cool.
Freeform allows you to create concepts impossible in COH.
It's a fairly easy game to solo.
It's not perfect, though.
Teaming is ... awkward. Leveling slows down DRASTICALLY doing regular missions when you team. When you share a mission so everyone can do it , you keep that mission once the team breaks up unless you abandon it.
The graphics are fairly cartoony. Really, I find a certain charm to them, now, but they do take some getting used to.
There are bugs that I wouldn't expect to find in a game that's as old as CO is.
It's not COX. If you go into CO expecting a COX experience, you are going to be disappointed.
But if you judge it by its own merits and criticize it for its own faults, then I think it's a fun game to play.