In an attempt to tackle this review in a light for those who have not seen it, I will do it in a means that diminishes the spoilers. Having said that, I cannot give my opinions unless I spoil some bits.
Surprise. Harrison Ford is in it.
Moving on, the fourth installment of this legendary series finds an aging Indiana Jones captured by Russian soldiers infiltrating an American military installation in search of a particular relic of paranormal value. This leads to a whole mess of Cold War intrigue and the search for, you guessed it: a temple of a crystal skull.
That said, real spoilers below:
Aliens? Really? Okay, one of the things I loved about the movies was that the movies, until the very end, tend to be very veiled and elusive about any supernatural elements that appear in the movie. The viewer does not really know what the Ark of the Covenant is until Indy chances upon it. This was scrapped.
From the very first scene in the movie, you see inklings of where they intend on going with the movie. You can tell that these are not suspiscions, or myths, or legends, but a very obvious nudge from Lucas that the cast and crew is going to run upon some Paranormal Psychic Activity (TM).
Also, it is a common trend in cinema to pick religion or extraterrestrials. It is against the rules to pick both.
Moving on, I have to say that Mr.Ford did a fairly convincing job of his role. He was not Rocky. He was not Rambo. He was not an old man trying to play an old man. He was an aging professor who happens to also have a side job raiding ruins. While he does perform a few stunts, they are with a dogged sort of endurance, instead of a youthful vigor.
Shia LaBoeuf's performance was wonderful only given how little he did. For an unfortunate speedbump of an actor, he did not prove particularly damaging to the movie's premise.
The score, as composed by John Williams, was fairly ignorable. Except for the powerful variations of the Indiana Jones theme, the score is unremarkable. This is likely because Williams knew that the audience would not care about anything other than the aforementioned variations.
The visuals were impressive, but largely unnecessary. One could tell that there were several CGI elements (read: animals) that ranged from completely superfluous to terribly infuriating. Without knowing one thing about the production, only Mr.Lucas' most recent movies, it is easy to see that he was making another self-satisfying piece of work that he can show to his grandchildren.
In a word: entertaining. In another word: awful. This movie is entertaining like Spider-Man 3 was entertaining. I enjoyed lampooning it. I enjoyed the mindless action. I enjoyed looking at Mary-Anne. This movie, however, is by far, the worst of the Indiana Jones franchise, though that does still leave it as a decent movie over all.