It's all that CGI.
The overuse of fuzzy, unconvincing computer-generated effects in Indiana Jones And The Kingdom Of The Crystal Skull is so prevalent, it repeatedly took me out of the movie, jerked me out of whatever spell it attempted to cast and reminded me of its own phoniness. And once that spell is broken, other deficiencies become so much more noticeable.
It starts out fine, with a nicely-staged action sequence in a secret Nevada military base (which also confirms that yes, Harrison Ford still has it--heck, he even looks a bit like mid-seventies Sean Connery), and a thrilling if improbable escape from an atomic blast. True, there are quibbles even here, but basically, we're off to a fine start.
But then Indy is whisked to an air force base for interrogation by sinister federal agents, and the establishing shot of the base seems to have been rendered almost entirely in the digital realm, with obviously artificial planes screaming overhead and a fleet of automobiles bearing a hazy, unconvincing look. Really? All that work for a simple establishing shot? You could have taken a camera out to any nondescript building, parked a period car in front of it, then cut to the scene.
The plot moves along--Spielberg certainly knows how to tell a story--with characters and situations introduced (or, in Karen Allen's case, re-introduced) at just the right intervals. The McGuffin in this case, the titular skull, seems a bit sillier than usual, and the movie treats it with needless seriousness, but okay. It's still pretty enjoyable...
...And then we get to what is obviously intended to be the big setpiece, a furious, elaborate chase through a Peruvian rain forest. Here, the CGI drives the entire sequence, and it becomes so overtly cartoonish--Shia LaBeouf straddling two vehicles, his lower body contorting in ways not possible in the natural world, then later vine-swinging through trees that are clearly nothing more than millions of pixels--that it's impossible to care what happens.
This sequence is obviously meant to recall the truck chase from Raiders Of The Lost Ark, but the problem is, as improbable as that sequence was, it was clearly being performed by real people, in real vehicles, on a real road. There's a feeling of danger, of excitement, in that scene that all the digital effects in the world can't conjure.
Which means that there's nothing to do during the chase scene in Crystal Skull than pick it apart, to wonder why the filmmakers thought a campy, frankly insulting vine-swinging scene was something that belonged in an Indiana Jones movie. (It reminded me of a similar regrettable scene in Octopussy; in fact, the jokey, self-conscious tone of Crystal Skull frequently reminds me of the worst of the Roger Moore-era Bond pictures.)
A later confrontation with an army of deadly but clearly computer-rendered ants is a nice homage to The Naked Jungle, but also reminds us that the snakes, bugs and rats Indy encountered in previous adventures were all the real deal and the expressions of discomfort on the actors' faces in those scenes were likely real, too. Here, the performers barely react--and why should they, since on the set they had nothing to react to?
It's all downhill from there--plunges off cliffs and down waterfalls that are obviously not real, an unsatisfying payoff to the story, a particularly undramatic resolution for Cate Blanchett's sneering commie villain, a climax heavily dependent on special effects--but in the age of CGI, the capacity of effects to astonish has been diminished, so this whole sequence just sits there.
But there is the final scene, which I loved, and which demonstrates the peculiar nature of this film: it's so close to being the real thing, so much they get right that it makes all the missteps that much more noticeable.
