Oh my word, just got back from this.
It's bad, and I mean really, really bad. Probably the worst film i've seen at the cinema.
People were walking out half way through, and I can honestly say i've never seen that. Terrible plot, terrible acting.... just terrible.
Avoid at all costs.
The worst film I've ever seen was buried. I left that film annoyed that I'd paid to see that piece of crap. On the plus side, it's opened my mind a bit to films which are pretty bad, I'd say Skyline was about a thousand times better, still poor but I'm thankful they didn't shoot the whole ***ing film in a box

That said, when I saw Mr Nice 3 people got up and left, with one just announcing "this is ****" as he left, the only film I've ever seen it happen in.
I'd probably give Skyline 3/10 - it was tedious and I was waiting for it to end, there was nothing original. I hadn't seen the trailer but I thought from the start of the film it had potential, and wasn't going to show you what was chasing them. Looks like there's going to be a sequel, don't think I'll be bothering with that though!