UMP doesn't need a review. It's that good.
Okay fine...
AEK: 4/5 Fast, accurate, powerful. Jack of all trades
XM8: 5/5 Great damage, okay recoil. Overall the best.
F2000: 3/5 Good at CQC, but overall outclassed by AEK.
AUG: 2/5 Not good for anything. The AR for hipsters.
AN-94: 3/5 An XM8 for people who can't burst properly.
HK416: 4/5 An XM8 for people who aren't as accurate.
M16: 3/5 An AEK for people who can't burst properly.
9A91: 3/5 Great power, poor ammo supply.
SCAR: 3/5 Slightly worse 9A with more ammo.
XM8C: 4/5 Great up close, lackluster at range. It's a true SMG.
AK74u: 3/5 Slightly worse XM8C, but still reliable.
Uzi: 4/5 Laser accurate aimed and hipfired.
PP2000: 4/5 Slightly worse Uzi with more ammo.
UMP: 5/5 High damage and super accurate. Easily the best.
PKM: 5/5 The king of damage output. Just don't get caught reloading.
SAW: 4/5 Mediocre damage, but great suppressing power and accuracy.
T88: 3/5 Good for sustained fire and little else. Sadly outclassed.
M60: 3/5 The pig has been neutered. Still usable, but nothing special.
XM8: 3/5 Average at everything. Great for obsessive reloaders.
MG36: 4/5 XM8 with the best sights in the game.
MG3: 3/5 PP2000 with extra ammo. I hope you like reloading.
M24: 4/5 Overall great. Sway only affects bad snipers.
T88: 4/5 Great damage output. Best suited for close and medium range.
SV98: 4/5 M24 with extra ammo.
SVU: 5/5 T88 with silencer. King of marksman rifles.
GOL: 4/5 M24 for girly men.
VSS: 5/5 SMG on steroids. Low recoil allows spray sniping as well as CQC dominance.
M95: 3/5 The gimmick sniper. Okay for body shots, but too slow overall.
M1A1: 3/5 Unsilenced SMG. Average and unremarkable.
M14: 4/5 T88 without a scope. Good ranged solution for non-Recons.
G3: 5/5 Huge power. Dominates for anyone who can control the recoil.
870: 3/5 Buckshot is powerful, but unreliable. Slugs are gimmicky snipers. Okay on smaller maps or on highly aggressive players.
SAIGA: 4/5 Powerful, reliable. Dominates anything within range.
SPAS: 2/5 The 870's fat cousin. The shotgun for hipsters.
USAS: 4/5 SAIGA for people who can't click fast.
NS2000: 3/5 The 870's muscular, athletic cousin.
M9: 4/5 Jack of all trades. The perfect sidearm.
Grach: 5/5 High fire rate, great damage. Excellent for CQC, great for medium as well.
M1911: 4/5 The best handgun for accurate players. Make every shot count.
Rex: 2/5 Too slow when the 1911 exists. Usable, but outclassed.
M93: 1/5 The Grach's special needs brother. Great at knifing range, terrible everywhere else.
Whew, that was tougher than I thought.