These are just my opinions. wanted to make it shorter so ididnt really proof read it.
add your opinions.

Sliding
Pros: Very cool, gets you into cover faster
Cons: Cockblocks you if you are moving and want to dropshot

Water
Pros: hiding for 3 seconds..
Cons: cant swim in deep water, can only hold breath for 5 seconds.

some other things i dont like; dogs i think have too much health, took 3 sniper bullets to kill it.
I.E.D's are too hard to see and nearly impossible to avoid once triggered.
Juggernaut maniac's are cool but waste of a kill streak

Things i do like: Sniping, probably the best sniping since mw2.
Oracle, nice killstreak reward, wish it lasted longer but whatever.
On-the-Go perk, great that you can finally sprint while reloading. (i usually swap out Slight of Hand for this)
Dead silence or amplify is a must have. also stalker is a great perk
Sights that can be put down while in game are very useful aswell