Great game...except for one thing...
I started on "normal" the first time through and I'm trying out "hard". I think by then you have it down to get moving through the levels. It will still be difficult ( with no health packs to carry and store for later on. You only get ones that increase you health when you walk over them from a limited amount of random guards. Once you finish hard I believe "silver weapons" are unlocked and that they have unlimited ammo ( not exactly sure about that since I haven't finished hard ).
Besides "BLACK" having the no save points...and buying it now for under $20.00 if you like shooters pick this one up!