Cliff Bleszinski said 90 minutes of game play, more like 20 minutes.
The deleted campaign scene starts off after Dom euthanizes his wife Maria. Marcus askes Dom if he wants to go after the queen guns blazing or stealth. This is where you decide, if you choose stealth, basically what happens is you go in disguised as Theron Guards and you cannot get to close to any locust or they will smell you. If you do get caught then you just fight them off from where you are, then you just go on and try it again. I thought it would be longer but it is actually really short, but it is fun. You also run into an old friend from Gears 1.
So thats enough for the deleted scene now to move on to the maps. If you buy the Dark Corners you get 7 maps and they are, War Machine from Gears 1, Allfathers Garden, Highway, Memorial, Nowhere, Way Station, and Sanctuary. The maps are all fun to play whether your playing online or with bots they are still fun. But if you don't have the other map packs I recommend you buy the All Fronts map pack, it saves you time and money.
So that is my review. So overall the Dark Corners Maps are great, the deleted scene is fun but really short. Overall I would give the deleted scene a 7.0 but the maps a 9.0 so overall that is an 7.5 to me, and if you have any questions feel free to ask.