I believe that it saves fairly often throughout. Even when looting hidden treasure or finding a viewpoint. If you do anything of slight importance it should auto-save your progress.
What are you using to play with?
Console or PC? If its with Console then it will save only during certain checkpoints in the games or when you complete one mission.
Hhhhhmmmm, interesting. I've been playing Brotherhood on PS3, so I can't recall its behavior with saving when I played AC2 on PC. I assumed that they were the same in that respect. Could be wrong... not the first time or the last.
well my problem is that i pass missions but when i try to load the game it loads from not the last autosave.. it's really embarassing and i have to pass missions a lot of times 🙁