Yeah it can be pretty hard and frustrating at certain times, though overall it's not that difficult. It's just these few specific sections that'll make you rage and want to hurt your controller or television set! As AFreakinCabbag3 mentioned, a lot of times I found that having your AI do a lot of the work does in fact save you some trouble. They are immortal and will often advance on their own as long as you tag along and don't get hurt too badly. I had the bad reflex of trying to advance too soon but the key is to sit back and work your way up progressively.
Prone prone prone!