1. 12 dead multiplayer maps, and dead community, no one to play it with. http://steamcharts.com/app/27330
2. Only gets played when there are cheap Steam sales or like the $1.29 Amazon.com sale right now, if that.
3. Multi-player is Peer 2 Peer matchmaking only, you host, non dedicated servers, can be lagging depending on the host and players.
4. Still contains Games For Windows Live DRM, that ends in July 2014.
5. Only 4 SP missions in the single player campaign, which is about 2-3 hours of total playtime.
6. Unreal Engine 3, with locked dev ~console.
7. No VAC or Evenbalance Punkbuster anti-cheat, the game features its own esp/wallhack called Hyper Reality Visor(HVR), still avaliable in Blacklight: Retribution.
8. Commercialism, static Alienware PC, Intel and ATI in game advertising.
Zombie Studios immediately bailed on this title and turned their focus to the Pay 2 Play model BlackLight Retribution after the games release. Blacklight: Retribution actually has a small player base and PunkBuster™ Anti-Cheat from Even Balance, Inc, you'd be better of playing that.
BlacklightTangoDown would be all right to kick the tires on for cheap with some friends that you know will play with you, but considering the all above drawbacks its probably best avoided, as its just something to end up sitting in your Steam Library.
note: and Steam dose not allow for text formatting, but allows for edit, just wow