From what I can tell, Millar is something of those writers who have an incredible disdain of classic superheroes. Wanted was as far from those characters as possible, the main character being basically Eminem as a gunslinging thrill-killing/raping supervillain in a world ruled by the top dogs of Evil.
Yeah, you're not alone in this. When I started reading Ultimate X-Men, I asked myself, "Jesus, who's this Millar guy? I understand why Bendis is around, he's funny, but Millar's like Liefeld's writing counterpart." I checked his Wikipedia entry to answer my question, and said "Oh, he did an Authority run. I guess he can't be that bad." I read Wanted after I heard it was being adapted for the screen, kinda enjoyed it for a miniseries about a bunch of characters I absolutely loathed, and felt better about the whole thing.
Then Civil War happened.
I remember thinking "Holy crap is this guy not in his right mind! What is he smoking? Can he write heroes at all? If he can, he's not having a good decade." Then for additional insult I read through all the Authority I could get my hands on. Warren Ellis started it out reeeeeal good, but then I hit Millar's run and it went DAMNED downhill (not to mention that they either got Frank Quitely before he was good or Millar's suck diffused into Quitely to maintain a proper balance of suck). I understand that it wasn't all his fault, that there may have been some crap editorial decisions handed down. But honestly, what proof alcohol was Marvel slipping in it's coffee to make that bad of a decision?
Ah Civil War.
I know a huge comic comunity in England, understandbly, a lot of them are incredibally peeved off with Civil War and they've all stopped buying it. Admitedly I've never read it, and not a big fan of Capin' America, but I personally think Millar just wanted attention, be it good or bad.
Marvel's Civil War was a big stinkeroo, but a lot of good stuff is coming about because it happened. There are a lot of good titles out now that, frankly, wouldn't have happened or become the way they are if all that garbage from Civil War hadn't played out. So ignore Civil War -- but check out some of the Initiative aftermath!
Basically in a nutshell, Millar made this big uproar and all it really was was him taking a dump on America and its biggest idol which was later killed by Ed Brubaker because he was bored and wanted Cap dead since he started writing it.