Way under rated. It makes me wonder if the critics really played at all.
First off, the campaign mode is really 10 challenge missions that can be played at 3 difficulty levels. Simular to Unit 13. For on the go, this is fine. Remember, COD games are primarily for online play.
Survival mode, if you like challenges, is awesome, even if your not killing waves of zombies. You start out with just a revolver and can change up to better weapon conveniently provided by each new wave by picking it up from the dead. Also by walking over corpes, you get more ammo.
Online play; This is were this game shines. Its a miniaturized, portable Black Ops online multiplayer that can literally be played on the go, anywhere (with wifi of course). Its 4 on 4 and has party mode for public or private and works great. In party mode you also have voice communication with party members through Vita mic & speakers if you didn't plug in a headset! That is nothing short of awesomeness. I teathered through my cell phone to play online and all I was getting was a 3G signal and play was no problem. Imagine being able to play Black Ops online potentially anywhere on a portable, well, isn't that worth a 10?
So far, 3 people whom I let play Black Ops Declassified online either have or plan to get the Vita/BO bundle. To heck with nay sayer critics.