I will talk as someone who hasn't played neither AC1 and AC3
AC2 was amazing, the fact that you had 4-5 cities to play really added lot of variety to the game, the mission really had lot of variety, and overall had a decent difficult. The story was cool since you needed to discover who was the mastermind in the whole thing, with the final stage being really awesome as it was a really cool mission. Hand to hand combat was easy, but still it was a bit hard when you were outnumbered.
AC2 is perfect, my major grip though, was that bullshit idea of locking 2 missions in the middle as DLC, whoever thought that was a cool idea, fuck him
Then we had Brotherhood, Rome was cool, but overall the game really feels like an expansion more than a new game, the novelty hasn't wore off yet, but still it feels weaker than AC2. The combats were easy though, to the point that lots of times I really didn't care if I was discovered by the guards, more when you had your disciples with a higl level, avaliable to do all the dirty work. The final battle was lame though, in the sense that it really feel a little off, in one second you were in rome, and suddenly you move to spain to fight the final battle. Cesar was a character that could have been better used IMO, in the sense too feel like an equal to ezio, where both had the same level of skill combats.
And then we had Revelations, Istanbul/Constantinice was an amazing setting, but at this point the missions really started to be a problem since were almost the same as the first 2 ezio games, it didn't helped that hand combat was way more easy, and that like someone said here in gaf this day, the final boss never felt like one, you suddenly defeated him and that was it
The cool thing was that it gave a good ending for both ezio and altair (the later was further explored with the that little animation movie), and the setup for AC3 was exciting, but overall was the most forgetable game of the 3 imo
