I enjoyed it but I'm a huge COD fan since when the first game came so it could be the worse game in the world I'd still love it.
Take out the little ones while hiding the entire time. ? it sounds like a very tedious battle. Once you've dealt with them, take out one of the big ones. The idea is to be patient and to watch the enemy movement for certain patterns and to find openings in those patterns. Sorry, it's the only help I can give. ?