Single player:
Overall very good. As average as the US Marine missions are, the Russian missions are amazing. I didn't notice endlessly respawning enemies either like in Modern Warfare. When you took enough out, your AI teammates would move forward and the mission would move along. The tank mission, sniper mission, and Catalina mission were all incredible.
Multi:
Just as good as 4 if not better thanks to more modes, better weapons and more authentic maps. Plus no more brown tone on everything.