I watched Dark Skies last night and my view is: as a sci-fi flick it was a complete waste of time (far too similar to The Forgotten), but as a scary movie, it worked really well.
Had to get a little closer to the missus a couple of times at the creepy bits, which is a good sign as it ain't a common event...
Big minus though is it really has to have a second part otherwise it is pointless.