A friend lent me the first season of MI:5, aka "Spooks" in the original BBC productions. Dunno why the name change, although in the US, the words is slang for ghosts, spies and a derogatory racial epithet - probably more people know the first and third definitions and hence the name change?
Watched the first two episodes, and several things stuck out:
The first story, about a right-to-life group and bombings, is heavily based on real-life US characters and events: so much so, that if the show had originally been produced in the US, there might have been legal threats. Also, the actress playing the lead guest character, who is supposed to have a southern US accent, has probably one of the worst ones I've ever heard. She's an American, too, so she has no excuse.
It's extremely amusing to listen to the British characters snark and snipe about the CIA and US politics in general. Especially when I apparently share the world-view of the characters doing the sniping...
The second episode, dealing with the racist, has one of the darkest endings I've seen on regular broadcast TV - it's interesting in a way, the character that gets killed in such a brutal and ugly way is a cast member, but it's only the second show so you're not sure who is a "protected" cast member and who is not, and the death is surprising. It leads me to believe that, were I a cast member on this show, I'd never be too uppity in my contract demands because my character would be killed off with a great deal of glee.
I like the principal actor, Matthew Macfadyen - though I've been warned not to get too fond of his character (this sounds ominous...) - he has a good, intense screen presence. The character of "Tessa" (actress Jenny Agutter) was driving me nuts, because I knew her face and voice, but couldn't place it - of course, it's because I was remembering a role she had (what, 30 years ago?) in Logan's Run. I also like the fact that the characters aren't perfect, and not even close. In the second episode, Tom screws up several times and it ends up with a rather high cost. Also, you know there is no way his romance will end well. No romance that contains the sentence "by the way, my real name is Tom, not Matthew, like I told you it was, and I'm a spy, not an IT expert" is going to end well. And, frankly, even though I like the character, I think she's better off without him. The rest of the cast is good, too, with Zoe being the "instantly likable" one (does that bode well for her? No, don't tell me.)