I thought this article from April was an accurate take on Gears of War. I'm not saying the author is correct, but that they make some sense. If you look at the setting from this standpoint, it's very depressing.
In thinking on the article, I was reminded of many of the games I tried to run in the late 1990s-early 2000s. They were very much like what the author describes. Given the group I was running for, I can see why the games failed. I don't think I knew how to phrase what I was trying to run and most of the audience would not have been receptive to this style of role playing game. You must sell it correctly, sell it to the right people, and make sure everyone (including yourself) understand the tone of the setting going in.
That said, I'm still more than willing to run a bleak setting like this in an rpg. It doesn't bother me one bit. I'm also looking forward to GoW3, reading more of the books, picking up the board game from Fantasy Flight Games, GoW4/Exile for the Kinect, and maybe even checking out the comic book series if it shows up in graphic novel format. I do love me some Gears.