Umm both have their pros and cons...
Save points are great cause if I mess up somewhere I can restart the thing from the place where I saved and autosaves just saves it at times where I've completely screwed up so at times you have to restart the mission or at times (God forbid) the whole God Damn Campaign...
However, the good thing about autosave is like, if something happens, like the game gets stuck or console shuts down for some reason, or you have to leave suddenly so you switch the console off, your game had already been saved so no problems. but when you have save points you'll have to repeat everything you've done starting from the last save point...
So like I said both have advantages and disadvantages...