I just returned my copy of the game the other day and decided to pop in here to laugh at the people saying this is too hard. I'm no pro gamer or anything, but FUBAR really isn't as bad as you guys make it out to be.
The only part that gave me any real problem was toward the end when there's like 3 turrets shooting at you at one time. But even then it probably took only 10-15 tries before I finally figured out the correct path.
Checkpoints are pretty frequent and there's no having to slog through big portions of the game if you die. As long as you aren't running around like an idiot and actually use the cover they give you you should be golden. Heck, half the time I just stayed in cover and let my teammates take everyone out. Sounds to me like you guys just don't have a whole lot of patience.