Michael Caine has been involved in some stinkers in his career (let's face it every actor has to pay the bills); he has also made plenty of very good films and also plenty of films like 'The Whistle-Blower': an above average and very watchable drama of the second-rank. In fact it's Caine's solid acting (mostly low-key though he does get to fly off the handle in his own inimitable style a couple of times) which invests the film with believable emotion and elevates it above it's many clichés. The supporting cast is strong too; a cynical, amoral, self-serving and oft sinister intelligence industry is portrayed ably by Gordon Jackson, James Fox and John Gielgud.
It's a shame that the demands of marketing mean that a film is often plugged as something it isn't. In this case 'The Whistle-Blower' is not a thriller (in fact the one and only 'action' scene - a car crash -is pretty rubbish and looks a bit tacked on), and it is only superficially a story about cold-war espionage (there are plenty of references to Anthony Blunt et al, but it's no 'Smiley's People'). Essentially it's a drama about loss; a man's loss of faith (in this case in his country) and, of his son. I'd point any harsh detractors of this film to the scene where, soon after learning of his sons death, Jones (Caine) attempts to discuss what happened with his son's neighbour and colleague, Rose (Dinah Stabb), and I challenge them not to be moved and at the same time chilled by the exchange.
Yes, this film does have plenty of flaws. Cinematically it is pretty dull and dated; it has a bit of that naff 1970's/80's home-counties feel to it (though in some ways one could argue I suppose that this style aids in the depiction of the stolid, grey, snobby, repressed British establishment of the story... an establishment trying to cope with it's diminished, subservient place in the world while keeping up the public pretence that Britannia still rules the waves). It's full of clichés and undeveloped characters, and the screen-play has plenty of downs as well as ups; but credit where credit is due, it is at times thought provoking and engaging. It shouldn't be put down for trying to cram a lot of things in and so appearing sometimes a bit unsubtle as a result (as I said previously it's no 'Smileys People').
I felt compelled to follow Jones' journey through a cynical, venal and uncaring world, and in that fundamental manner, for me, the film is a success.