J'kar fails to mention the fact he's playing the game on Easy. Of course the bosses don't seem that difficult. The mode of difficulty really changes the aggression and damage of the bosses. After beating Cerberus on Normal, I went back on Easy and fought him, and I couldn't believe it was the same boss. He barely ever attacks, he just sits there and takes it, and when he does hit you, he does a sliver of damage. It was pathetic.
I wouldn't be too proud of killing the Mission 5 boss on Easy mode. On harder difficulties, constantly moving around is something you're forced to do just to stay alive, nevermind attack. Easy mode requires less skill and far less strategy, especially in fighting bosses.
Right now I'm at the mission where you have to fight Vergil for the second time. I don't know the mission number, but it's around 13 or 14. I just got Quicksilver, and I have to say, that horse was possibly the easiest boss so far, not including Mission 2
Edit: Scratch that, Vergil the first time was the easiest boss so far, with the horse in a close second. I'm assuming Vergil's going to be a little harder this time around, with that really homosexual light-feather crap.