worth a rental
I don't know how this game plays on the easier difficulties, because I beat it on hard. However, if I only played Gears of War on casual I would have thought aht game sucked monkey balls. Gears of War was only fun on the harder settings, and I think it is the same for Blacksite Area 51.
The gameplay is varied enough, and honestly, that is the only thing this game has going for it. But in the old days we didn't play games for a story did we? For this reason alone it is not worth buying. If it had a good story that kept you playing, it still would not be worth owning because there is no one playing online. But it would at least make it worth renting for $8 or buy it used.
Again it is however worth adding to your que if you have played everything else that you have been wanting to play.
Jericho was a better game if that means anything to you. But I sort of liked Jericho. Heck I beat both games so that means I enjoyed them well enough.
The graphics are good enough, and so it the sound. Story sort of blows.