It's an average FPS with somewhat worse than average AI and some nice destructible objects.
First, I'm not sure that you could find one marketing department that after such a long game development would release a game the same week Crysis was scheduled to come out -- games are expensive and a few people would choose Blacksite over Crysis (especially with some excellent games like CoD4 released a week before that).
Second, the very promised co-op was dropped at the last moment. The official website was still saying great things about the game LAN and Internet co-op while the company shipped the game without this co-op feature.
Third, even after such a long development the game is not optimized very well. The graphics appear slightly better than mediocre at its highest settings (far worse than in the official movies or screenshots). However even on systems that can handle this game at its highest settings with ease there are significant number of frame rate drops which just spoils whatever good impression you got from the game engine.
Fourth, the game comes on two install DVDs ... wtf ... if Crysis and all recent games (long and short) can fit on one DVD why would developer or publisher need to put this game on two. 15 GB required disk space? BTW, the game options settings are also somewhat bizarrely set with rather minimalistic video/graphics options.
Overall, this is not such a bad game as I described it above (I'm mostly pissed about the co-op being dropped). It's an average FPS with somewhat worse than average AI and some nice destructible objects. The game "morale" concept is pretty much useless. Weapons feel good and their sound is pretty good too, tho they seem to be a bit too accurate to be "realistic". The story ... not sure if there is any or if it's important at all. Maybe if you can identify yourself with your game character it could increase the potential of this game ... but, pretty much you are a generic Joe killing generic enemies. The game gets a bit better after a first few levels, but needs some serious patching. If this game totally fails, it will boil down to the broken "promises" (co-op) and sloppy quality control as the reasons why.
[ 11/22/07 Note: It seems the developer has been busy addressing all the bugs and reported problems with this game, so they issued already two patches within a week. The latest one (v.1.2 around 115 MB) is at the bottom of this page:
http://www.blacksitegame.com/. Frankly, more patching is needed or at least I haven't noticed much difference]