Champions is neither really good, or really bad. It has an extensive character creation to it, a nicely built nemesis system to attempt to give light to your characters own superhero "story", and the action is nicely paced, and not too fast or slow.

All that said, there are some oddities to it, that I'm hoping are improved, like more variations between what to do between levels, there isn't much varied content, once you make your nemesis that's as non-linear as the game gets, there seems to be set stories (which in truth isn't all that bad) but sometimes it just doesn't feel very superheroish as CoH captured with things like TaskForces and what not. A lot of people pointed out that there needs to be some adjusting in the powersets and overall balance. I've experienced that trying to create your own "specialized" powerset can possibly gimp you sevrely as to someone who is a pure powerset. Picking skills, though its free for all kinda set, you pick what you want and can test it out before finalizing it, to me for some powersets, it felt like I had to take this skill or basically I'd be shooting myself in the foot.

All and all Champions is a well placed follow up to City of Heroes (being as Cryptic helped out with the CoH IP), and there are some similiarites that show strongly. There are still needs for improvment, a lot of things to be added to keep people busy other than special events, like what has happened today with Dr. Destroyer and his robots trying to invade Millennium City. If you like CoH, you'll probably like Champions without a question, they are practically identical. If you're looking for a more pvp oriented game I'd stick with Aion.

Champion's pvp isn't all that great, some people like it, but to me its just a clash mash up of who can spam skills the fastest, then again every pvp system is like that. I just found pvp to be more unrewarding (though I did get a title from it called Ceiling Cat >.>)
Its not all that fleshed out, its more button mashing and who has the best synergy between endurance and skills. Aion's pvp system for me was a lot more rewarding (whether it be getting ganked, ganking, or actual decent fights) and had a better feel. So if you're looking for a more pvp orientated game go with Aion.