Review will not spoil the BIG secret of the movie, but you've been warned regardless.
The thing about the Indiana Jones movies is, aside from the original "Raiders of The Lost Ark," none of them have been 'necessary.' This isn't like the "Star Wars" franchise, where each installment adds new information and beats to a continuing larger story - "Raiders" was a complete stand-alone film with nothing left undone or unsaid, and thus ALL the subsequent returns of the character have been essentially superfluous. "Temple of Doom" and "Last Crusade" don't really have any (major) greater-truths to reveal or broader continuity to flesh out - fine films in their own right they may be - they exist simply because Indiana Jones and his world are fun to revisit.
Keeping that in perspective has been on my mind since it was first announced that Steven Spielberg, George Lucas and Harrison Ford were going back to the character one more time. It's not so much a lowering of expectations as it is an honest assessment. The now-legendary sense of deflation fans felt as the "Star Wars" prequels unfolded had to do with a genuine drop in quality: The original SW trilogy were both grandly-mounted films and the foundation of one of the great modern pop-cultural mythologies - a standard the prequels simply failed to live up to.
The two (now three) post-"Raiders" Indy movies are of a different breed: They're romps; big showy collections of action and FX setpieces given a MASSIVE gravitas-injection by their connection to the original film... a summation that applies quite handily to the newest installment. I do suspect, though, that the nearly two-DECADES of wait between the previous sequel and this most-recent one may lead some to be expecting something that they really oughtn't be - this just isn't a series that's going to lend itself to some final "deepening." What we get from "Crystal Skull" is the same basic thing we got from "Temple" and "Crusade" - a cracking-good adventure flick with some excellent action beats, lifted from good to great by the presence of the iconic elements (hat, whip, snakes, John Williams' score) from "Raiders."
It's actually surprisingly hard to "review" in any great detail WITHOUT getting into spoilers. Since the hype-machine was able to do all it needed to on the simple declaration that a new Indiana Jones movie was coming out, we've been spared the usual issue of having the whole movie given away in the trailers. Just describing what the titular Crystal Skull IS or what certain character's relationships are would qualify as major reveals. Heck, the film's OPENING SCENE involves the biggest moment of inter-sequel connectivity in the entire series, and segues moments later into a reveal that sends the story off in a direction so profoundly different from anything else in the series it's rather jarring (honestly, I won't be surprised if some audiences find how "out there" this installment gets to be just too much for them.)
In any case, the non-spoiler setup goes something like this: It's now 1957, and Indy has spent the 19 years between finding the Holy Grail and "now" doing vaugely eluded-to military/spy work against The Russians. A few details of said work have garnered him the attention of Irina Spalko (Cate Blanchett, modeling this years hot new look for professional dominatrixes with movie-buff clients) a Soviet agent and self-professed psychic hot on the trail of a legendary Mayan artifact called "The Crystal Skull" in the hope that it can be turned into a powerful "psychic weapon." Spalko's harassments eventually put Indy into contact with young greaser Mutt Williams (Shia LeBouf) who was told to get Dr. Jones' help rescuing his mother and a professor pal of Indy's (John Hurt) both of who have been kidnapped by the Reds. From there on, Act 2 is combination old/young buddy movie and detective story as Indy and Mutt bond while chasing down clues one step behind Spalko and try to figure out what's REALLY going on with the Skull.
After that, the MAJOR SPOILERS start up again force and don't let up - but all you really need to know is that this IS an Indiana Jones movie and thus the third act is a series of extended action/chase scenes followed by a big light-show. The majority of it works tremendously, especially a multi-vehicle race/brawl and an appearance by some nasty insects; while some of it borders on the silly (a cliff-jump gag and a vine-swing scene are a bit much) but it's never boring and the staging - while a bit too reliant on CGI - is top shelf. Nobody does this stuff like Steven Spielberg, nobody.
Thing is, there's really no way of telling whether or not this film would be as much fun as it is sans the iconic characters and the music, but that's not really a functional question. What it boils down to is that the film delivers another big, fun adventure with Indiana Jones. That's the only standard it needed to meet, and I consider it met. Now go see it so you can find out all the stuff I couldn't talk about.
FINAL RATING: 7/10