DH and I went to see this yesterday and enjoyed it enormously.
I know there is a separate forum for Films but I thought I would post this here because, TBH, it felt to me more like a feature length version of the TV programme and I think anyone who enjoyed the TV programme would like this.
Some of the reviews have been a bit sniffy about it. But I suspect that if you are not familiar with Spooks and just take the film on its own merits and compare it with, say, a Bond or a Mission Impossible or something it might not seem to measure up. However, to other fans I would recommend it. There are a few nice nods towards the fandom which I won't mention in the interest of not revealing spoilers 
Oh and Kit Haringtom fans will probably enjoy it