Hello. I've just grabbed the trial myself (after, oddly enough, replaying the KotOR games... AND Jedi Academy!) and realized that I really did want to give SWG another look. I betad and wasn't in love with it. Well, it's turning out to be a blast and I am fair certain I'll buy it and keep playing, especially if I can find RP buddies.
As a player of CoH/CoV, my experiences so far are that I've had lots more fun in SWG. It's no one thing that is different that makes or breaks the experience. I love supers; I love Star Wars. The comparison isn't apples and oranges, it's apples and doughnuts. What everyone else says is true: give it a whirl.
Can you just whip up a character and kill stuff? Yes. Is it as fun as playing through some of the quests? Doesn't seem to be. For just killing away I usually grab a console game with zombies. Lots of zombies.
In regards to your server-related questions: There is a whole list of servers and what their specialty seems to be if you google or hit a site like allakhazam.com and go through their SWG section. I'm at Starsider currently, one of the unofficial RP servers (kind of like Virtue in CoH/CoV). I'll probably hit one of the GCW (Galactic Civil War aka PVP) servers as well, as PVP can often turn one game into an entirely new game.
Character classes seem to be fairly unique when compared to many other MMOs though the comparisons to CoH/CoV would be closest (as opposed to, say, EQ or WoW or LotRO -- I'm not in the Warhammer beta and can't discuss Stargate Worlds with any authority) so you'd probably feel pretty at-home with roles. The game seems well-designed for the casual player to be able to play and level without spending three hours to get a group for a 45-minute instance (or 12-minute group quest! -- FFXI, are you listening?).
I hope you give it a go and post your feedback here, I'm curious to see how another CoH veteran finds SWG.