Sorry to disappoint those who are eagerly awaiting their chance to see the next Indiana Jones movie, but the series should have ended with the third movie. Here are my reasons:
1. To start with, the third movie, Indiana Jones and the Last Crusade, ended with Indy and his dad drinking from the holy grail, thus assuring their story of immortality. Then they, Marcus Brodie, and Salah ride off into the sunset. A perfectly satisfying conclusion to the Indiana Jones chronicles.
2. The present movie, Indiana Jones and the Kingdom of the Crystal Skull, relied too heavily upon the past, essentially gratifying someone's ego--individually or collectively, I'm not willing to guess. Karen Allen and her character Marian Ravenwood were excellent in the first episode, Raiders of the Lost Ark. Bringing her back into the present after so many years to reprise her role as Indy's on-again/off-again lover was tantamount to a soap opera ploy, beneath Spielberg's and Lucas' imagination. Or so I thought.
3. Although this fourth installment has great action and suspense, the writing, acting, and production values all could have used more work; again, relying too heavily upon the past, especially the aging talents of their actors (despite that sip from the grail).
The palette of the film was too drab. The only 'pop' was during the scene shot in New Haven made to look like a '50's style soda shop. (Also, if you know New Haven and Yale University, it's fun to recognize familiar sights.) Cate Blanchett's character had black shiny hair and wore a light gray jumpsuit during the whole film. It would have been more dramatic to see her slip into something more feminine and colorful, perhaps allowing for some of that witty repartee that Indy is known to engage in with his female nemesis. It also would have given her character a little more depth.
As for the writing, the story of the movie was a bit farfetched (every Indiana Jones film has a story: the lost ark, Kali and the shankara stones, the search for the holy grail), bordering on science fiction rather than Indy's field of archaeology. Some of the subplots were also slipping into soap opera territory, which I outgrew in my twenties. And a few stunts were just outrageous, in that it would be highly unlikely that anyone else could have survived them.
4. Finally, the last 1/2 hour of the movie so closely resembled the last 1/2 hour of National Treasure: Book of Secrets you'd think someone got their hands on the storyboards.
Again, sorry to disappoint, but either go see a matinee to save a few bucks or wait for the DVD and watch it on a friend's big screen TV.