User blog comment:Dryls/Dark Souls Vs. Dark Souls II/@comment-76.121.58.41-20150809075330

Actually, in Dark Souls I, from what I remember, you could technically roll through most attacks like in Dark Souls II. It's just that in Dark Souls II, the adaptability stat helps determine the amount of invincibility frames you have in a roll. So at the start of the game, you won't have as many i-frames so rolling will be a bit harder until you increase your adaptability stat and bring it up to the levels of Dark Souls I and maybe even beyond.

Also, I would say that backstabbing is harder in Dark Souls II, there's some start up frames to the backstab that your opponent could get out of, probably so that PVP isn't a backstab fest like in the first game.