First 2-3 seasons are good, I enjoyed them. (I watched through season 5 or maybe 6, it's been awhile, on Netlix.)
Then I think around season 4 or 5 they started to get heavy into anti-American BS every episode. 9/11 was our own fault, U.S. solders butcher Iraqi civilians for kicks and giggles, we're destroying the planet with out SUVs, the CIA tortures the poor tewworists, we trample every other countries sovereignty blah..blah you know the same old tired anti-American rhetoric. Maybe the British audience goes for that kind of stuff (I believe the show original title is "Spooks" in the UK) but it sure doesn't play with me.
Then to top it off, the one character who use to be bad-arse (Adam I think) suddenly turns into a whiny, skirt-chasing pansy between 2 seasons. Then he got killed thank goodness (they kill off major characters all the time) but I was through with the series by then anyway.