Matthew Macfadyen, Keeley Hawes, David Oyelowo, Peter Firth, Hugh Simon, Shauna Macdonald, Rory MacGregor, Natasha Little, Nicola Walker, Megan Dodds, Jenny Agutter and Enzo Cilenti are listed as the main cast.

"[10] Dennis Landmann of MovieFreak stated that the season "rules" as it "tells complex, dangerous, and relevant stories that creates high octane, powerful drama", and the producers "create top notch work, from the excellent cinematography to the great-looking sets and locations, and from well researched and sweet scripts to solid acting by the principal actors."

Landmann noticed the main focus towards Tom throughout the series that builds until he "becomes somewhat of a haunted soul" with the final minutes being "so powerful they affected how I felt for the next couple of days; I kept thinking about the character and the tragic events that happened to him".

There is nothing worse than the cynical disbelief of an action/drama show where you know the main characters are going to escape without any harm, because hey, they're the good guys, and they have to come back and make a new season.

It keeps you on your toes.Michael Mackenzie of The Digital Fix commented that "the chain events leading up to the chaotic final episode" was "extremely set up", even though he opined that Macfadyen had "always been the weakest actor in the ensemble".

Arseneau stated that it clicks "on nearly every level required: great acting performances, fantastic story lines, well-written dialogue, gritty authenticity, and most importantly, unpredictability," summing the series as "sleek, stylish, tense, and compelling—some of the best television I have had the pleasure to watch".

Ordway further felt it was "poorly acted", the rapid cuts and frantic editing "doesn't work" to make it more entertaining, and that the attempts for complexity were "painful".

Instead of being a well-informed piece of film-making, this episode of Spooks pandered to grossly offensive and Islamophobic caricatures of imams, Muslim students and mosques.

"[27] Ahtsham Ali of the Islamic Society of Britain claimed that the episode "adds fuel to the fire of already negative perceptions of Muslims and fans the flames of British National Party rhetoric.

"[28] Muslim Parliament of Great Britain's Dr Ghayasuddin Siddiqui said "It is sad the BBC is doing this, [...] We are trying to condemn this kind of involvement in our community...to keep on making us look responsible for these crimes is just manipulation.

The producers stated that the episode was not meant to offend anybody, and that it did not imply that all Muslims are terrorists, only that "some fanatics" can give "millions of good people a bad name.

Paul Knight and Barney Pilling were nominated for a British Academy Television (BAFTA) Craft award for Editing in Fiction/Entertainment, but lost out to Mark Day for his work on the 2003 serial State of Play.

[39] The second series cliffhanger was the public's second favourite moment in television, beaten only by the surprise return of "Dirty Den" Watts from the soap opera EastEnders.

In the United Kingdom, the box set was released with a "15" British Board of Film Classification (BBFC) certificate (meaning it is unsuitable for viewing by those under the age of 15 years).