Spooks: The Greater Good (2015) - Movie Review

Based upon the BBC Television series that ran from 2002-11, Spooks: The Greater Good is a film continuation of the series currently in cinemas.
I feel that this is a film that I would enjoy much more having seen the Spooks TV series, with our main character Harry Pearce seeming to be concluding a pre-established character arc, with him facing his failure and doing whatever he can to make it right, as the film's subtitle says, for the greater good.
This character arc's conclusion in the film is a distinct problem for newcomers, as so much is mentioned about Harry as if you're meant to know all of this as a viewer, and tries to set him up as the ultimate protagonist of the film whom nobody can quite trust.
What's even more confusing for the film is that it also includes Kit Harrington as Will Holloway, a new character for the film who one would have thought would be the new audience's eyes into the story, but the screenplay never seems to actually set up his character and he simply seems to be the troubled hero who needs to solve the problem.
The other characters are also just there for newcomers, with again no real establishment, meaning that we just have to assume that Holloway is the only character we can truly trust, even though long-time viewers would be trusting Harry throughout the film. This all seems incredibly unfocused from a screenplay point of view, and makes the film difficult to follow character-wise for new viewers such as myself. In fact, writing this I have no idea if I've misunderstood the film because I haven't seen the TV series and the screenplay doesn't give me the necessary information. I understand that this film is tailored more towards long-time viewers, but all the characters know information newcomers don't. There are no 'newcomer' characters to be a new audiences' eyes and ears throughout the story. There was even one character who just appeared in two scenes with no real name or purpose other than to just be the tech-guy for Harry, meaning that I felt incredibly confused as to who this random character was in the film.
The story did, however, feel like a big scale story being told on a small-scale budget, resulting in rather uninteresting locations for a spy movie, fairly dull action sequences and lacked much scope to it all. Sometimes a small budget can make a film really try hard with the characters and storyline, like Dr. Horrible's Sing-a-Long Blog (2008), which had hardly any budget but still managed to tell the story without seeming limited by money. I understand that this is only a motion picture continuation of the Spooks Television series, but perhaps they could have tried to tell the story for a new audience, and perhaps gotten an American studio to put some money into it to try and attract a larger audience. The whole film just doesn't have much of the scale it tries to have. That said, some of the London locations looked great.
The music by Dominic Lewis was really good, and I loved the electronic-synth feel to it. There didn't seem to be much for the action sequences, but I understand that Lewis didn't want to overdo it as some films would. The direction and cinematography was pretty good, and the writing solid enough.
I can't say that I didn't like Spooks: The Greater Good, I can just say that I thought it was a solid spy flick, and nothing more. Perhaps had I seen the TV show, I could have gotten more of an opinion on this, but it didn't really do much for me and I'm sure it'll be forgotten by the end of the year. At the end of the day, it just didn't do anything for me. That's probably why it took me so long to write this review.