Let me preface my comments by saying that I loved Clancy's book when I first read it ten years ago. It was a gripping page-turner, and a marvelously intricate work, building suspense in layers. I've since re-read it several times.
I realistically expected that elements of the massive tome would have to be changed or condensed for the screen version. But so much is changed, and so many critical elements removed, that it hardly resembles its novel origins. As a result I find it difficult to believe that Tom Clancy had much creative control over this effort, though he's credited as "Executive Producer".
First, for some inexplicable reason, this movie jumps away from previous Clancy continuity by completely revamping the character of Jack Ryan. Rather than a middle aged CIA administrator, Ryan is now a young handsome PhD with little Washington experience. Apparently this is to boost the "chick-flick" quotient of this outing, as it adds nothing tangible to the film, and only detracts from the continuity that had been built to this point. There's even a scene where Kathy is asked how "cute" Ryan is on a 1-10 scale, and she says a "12". Ugh! They had time to include this garbage, yet skip vital character development later in the film?
Yet, even worse, this Ryan is the Uber-Ryan. Yes, the man is everywhere, and involved in virtually every action sequence in the film. He finds the bomb lab in Russia (and saves Clark, CLARK, for crying out loud, shouldn't it be the OTHER way around???), races to Baltimore in a helicopter to warn President Fowler(who in yet another huge change is caught in the blast himself) he gets caught in the nuclear blast(and hardly gets his hair mussed, how cliche!), he personally sifts through the rubble of Baltimore for evidence (another inexplicable change, as Denver was the city nuked in the book, then goes on for a cliched confrontation with the terrorists (who are VERY poorly developed character-wise, totally unlike the book) mano y mano in a darkened Baltimore warehouse. Oh, and I almost forgot, there was the obligatory (and oh so overused) Hollywood "death" scene where Ryan (again, Ryan personally) kneels at the bed of Morgan Freeman as he expires in a "tearful" sequence. Yes, it was painful but not in the way intended.
I thought Clancy's books sometimes stretched the believablity of Ryan's capabilities to the breaking point, yet this goes way beyond anything Clancy has previously done. It's Super-Ryan to the rescue, more 007 than distinguished, cerebral CIA analyst, even though he supposedly had little if any experience in espionage, forensics, or any of that. It is very cliched, and very tiresome to watch, at least for anyone that's actually read the books.
One of the best parts of the novel was the realism. Reading it, you really believed that the plot Clancy put in motion could occur. Not this movie. Believable Islamic terrorists were replaced with cartoonish middle-aged white european neo-Nazis who make stock Hitler-loving speeches that any avid movie-goer has heard a million times before. Dr. Evil would love these guys. They even got to kill one of their own rank, ala Dr. Evil, after he experienced the convenient cinematic "crisis of concience". You could see it coming a mile away! I guess that's so we can understand these men are serious and mean "business"
Oh and on the subject of business, since the typical european Neo-Nazi is young, skinheaded, devoted, but not terribly affluent these Nazis were conveniently well-to-do businessmen with the financial assets and experience to put their scheme in motion. Is this Tom Clancy or James Bond? I guess its not "politically correct" to feature the actual type of real world Middle Eastern "gentlemen", with the aid of foreign government sponsorship who even now are striving, again in reality, to make weapons of mass destruction to use against us? I guess its always "safe" to once again bash caucasian conservative-appearing men in business suits. Whatever the reason, its another major plot element from the book down the tubes.
On the subject of the bomb; there was a great deal of detail in the book about the bomb that was completely overlooked in the movie. For example, in the book, the bomb was originally intended to be a multi-stage, ie, HYDROGEN bomb. It fizzled. The original yield was overestimated by twenty fold by military analysts because of reflection of the snow, and other factors. The President's advisors didn't think terrorists could build a multi-stage weapon, thus the suspicion was immediately upon the Russians. It was only after frantic detective work that the true yield of the bomb was discovered, and it put Ryan on the proper track AND gave him leverage to help defuse the situation(no pun intended). It's a common worry that terrorist groups might get ahold of a low yield fission "suitcase" bombs, yet right from the start in the movie no one, including the President, suspects terrorists!
Another fond memory I have of the book is that Clancy took us to the very brink of Armageddon where the US and Russia were nearly in a shooting war because of the misinterpreted size of the bomb, and the tank battle that the German terrorists cause to happen in Berlin. Yet here, the Russians attack and virtually destroy a US nuclear carrier, we bomb a Russian airbase, and we're still standing at that brink. Somehow, I think if events got that far, there'd be no turning back. Clancy seemed to know that when he wrote the book; he seems to have forgotten it here though.
These are just a few of the major problems with this film. The pacing is bad; one minute the bomb is still being constructed, and a few minutes later its already placed in Baltimore and about to explode, with the cliche of Ryan hot on the trail, trying to warn the President. In the book, the bomb catches everyone completely off-guard, but not here, ANOTHER irritating change. There is also very little character development, the President's motivations are poorly understood, the paranoia of Fowler over the new Russian President's motives was poorly developed, etc etc.
Avoid it if you can. I turned the last 5 minutes off, it was so bad.