Now that the pack has been out a while I have to say my personal tier list of maps is
Most enjoyable maps
Maps fun to play on especially with the right game mode
Meh, the maps are okay but I'd rather avoid if possible
Start, Up, A, Up, A
As for the Peacekeeper, I find it's a decent weapon, does what it's meant to do pretty well and that's be a SMG but with a bit of range. Personally I prefer to use my AN-94 if I'm expecting a fair bit of mid-long range combat and will just pick a SMG (other than the Peacekeeper) or a Shotgun if I'm going to be be doing close quarter combat.