I was on the second to last stage last night and finally turned the game off in frustration and won't be playing it again. It sold on Ebay this morning.
The checkpoints (on middle difficulty) are to far apart or are spaced such that you have to backtrack A LOT if you die. I found myself becoming furious at 3 different areas and then in second to last stage, after clearing the artillery and then the second house, I ran around back, the gates popped open and three guys blasted me dead in about 1/4 second. No chance to get away or respond. What does the game do? Kicks me back to the previous save point which was probably 15-20 minutes of playing. That was the last straw.
Great game. Sucky implementation of the save mechanics. I don't mind it being hard. I don't mind dieing and having to play from the latest save point. I do mind backtracking, however. That's utter BS. Way to go, EA. I guess they don't have play testers.