Aye, found that out the other day, luckily before I played either. 
 Assassin's Creed II
Assassin's Creed II done.  I even bothered to Platinum it, and I must say it was probably the easiest Platinum I ever got.  The story was great and I liked that I could upgrade Montewhatever's shops and whatnot.  I felt the fights in AC were a bit better than the ones in ACII for some reason I'm not sure of, maybe I just never got the hang of it.
If 
Assassin's Creed: Brotherhood hasn't changed the battle system, though, then I've definitely got the hang of it now, because I love this game more than the previous two by some distance because of one reason alone: Recruiting other assassin's.  Oh man, I love sitting around the coops and sending them on missions and leveling them up and whatnot.  Most of mine are up to level 8 now, although I still need to get a couple more towers down so I can unlock my last two recruits.  I'm not sure I can be arsed getting 100% synchronisation, though.  Some of the requirements are just not worth my time... maybe when I'm done.  I dunno.
I got tired of trying to beat something "the right way" at some point and just sat on a bench and highlighted who I wanted dead and called out my crew, and they stormed the place while I chilled out.  It was great.  I like to assume that this is what it looks like when I'm making my kills, when seen from a civilian perspective.  Guy's walking along, minding his own business, BAM, assassin jumps from alley and murders him.  Patrol dude on a horse?  BAM.  Assassin runs up, pulls him off, kills him, mounts the horse, horse rears back and whinnies for dramatic effect and then my assassin rides it off into the distance.  Awesome.