I watched Indiana Jones and the Kingdom of the Crystal Skull some days ago, but I've needed a couple of days to think about it and process what I've seen. I know it's disappointed a lot of people, and, admittedly, it does not really seem like an Indiana Jones flick proper to me. While it has the action, dynamics and inter-character chemistry of the original Indy-trilogy, it did remind me more of the LucasFilm Games (as they were called back then) classics, ZakMcKracken and the Alien Mindbenders or The Dig. It would have worked much better as a Zak McKracken filmatization of sorts than an Indy-flick. I am still ambivalent about Indiana Jones and the Kingdom of the Crystal Skull; I just don't know what to make of it, but at least I was entertained when I saw it.

The good
The title: Indiana Jones and the Kingdom of the Crystal Skull is a very long, B-movieish title... and I love it. I've always liked the titles of the Indy-flicks. They promise action, fun and adventure and they are totally true to the spirit of the "X and the Y of the Z" titles of books, movies, comics books etc. of the adventure genre of the 30s, 40s, 50s, and 60s. Indiana Jones and the Temple of Doom has always been my favorite Indy-title (not my favorite Indy-movie though - that would be Indiana Jones and the Last Crusade) simply because "temple" and "doom" appear in it. But Indiana Jones and the Kingdom of the Crystal Skull comes close because it contains cool words like "kingdom" and "skull". The title surely spells adventure of the Indy-kind, and we do get adventure, but, unfortunately, not always of the Indy-kind.
Coherence in 50s themes: I like that this movie integrates a lot of themes that were relevant to the 50s such as the Cold War and the Red Scare, Area 51 and the UFO phenomena, Rock 'n' Roll, nuclear bombs etc. This doesn't mean that I like all of the themes, as you'll see in the The Bad section, but I do like that the movie manages to capture a lot of the 50s spirit just like the prequels captured a lot of the (pre-)WWII spirit.
Mutt/Labeouf: Shia LaBeouf is a great actor (it was basically his performance that made The Transformers a positive cinematic experience), and he portrays the new character of Mutt very well. I did predict that Mutt was Indy's son (but who didn't?), and it works very well. In many ways, he is the 50s version of the unsettled Indy that we see in the Young Indy-series. Mutt certainly would be an interesting character to carry on the Henry Jones torch when the time comes, although The Adventures of Mutt Jones doesn't sound that well.
Ravenwood/Allen: the original Indiana Jones lady is back. She was great in Raiders and it's just great to see her in an Indy-flick again.
Campus car chase: one of my favorite scenes of the movie, and a real Indy-action scene. My favorite part is in the library when Indy starts lecturing that student about diffusionism and what it takes to be a good archaeologist. I like this because it is hilarious, and it relates to a side of Indy that has always been there, but which we do not really see in the prequels - namely, Indy the scholar.
"Quicksand" scene: another scene that captures Indy the scholar. The snake part is funny, and what would an Indy-film be without reference to his fear of snakes, but what I really liked was when Indy starts lecturing Mutt on the differences between quicksand and dry-sand-pits.
Indy-Mutt chemistry: The chemistry between Indy and Mutt is also very funny and full of references to the relationship between Indy and Henry Jones Sr. in Crusade with Indy even uttering lines like "This is intolerable" and so on.
Dialogue: This film does have much more dialogue than the prequels, but I think most of the dialogue actually works quite well, and a lot of it is very funny too.
Fencing: I like the Mutt vs. Spalko fencing scene (apart from the fact that the CGI effects are quite bad at times). It's a real Indy-action sequence. Not as cool as the truck fight of Raiders or the mine cart chase of Temple, and certainly not the tank scene in Crusade, but it certainly is a true Indy action sequence (although it's Mutt and not Indy who's in it).
Paramount gopher hill: very funny... until that damn gopher appears.
References to Marcus Brody: I just liked them... probably because I like the Brody character in Crusade.

The bad
Aliens: Aliens?!?! That is really so non-Indy. Aliens are totally out of line with the Indy-continuity with its references to religion and tradition. It's not that I have any problems with aliens as such... I am a sci-fi fan after all. They just don't fit into the Indy-world at all. This is basically, what makes me not consider this a real Indy-flick. It would have been okay, I guess, if the whole alien thing was just implied as a possibility. That would have been cool, but that we have to actually see them a couple of times through out the movie just does it. And the flying saucer at the end is just ridiculous. It would have worked much better in a Zak McKracken filmatization. But not in Indy. It's just incompatible with Indy.
No nazis: Okay, it would be too anachronistic with Nazis in 57, but the Soviets just don't work as well as the Nazis. I guess that the Soviet stereotype just isn't as effective or well-known throughout the world as the Nazi stereotype is. Also, the Nazis are a bit like stormtroopers in Star Wars. Watching a Star Wars movie without stormtroopers just doesn't feel right. Sure, there are clone troopers, but they're just not stormtroopers, are they? Anyhow, the Soviets are obviously meant to have the same function as the Nazis - they certainly do the same things - it just doesn't work as well with Soviets as with Nazis.
Psychic stuff: while the psychic stuff actually does relate to some popular folk theories about crystal skull, it seems out of place in an Indy-flick... certainly one that has aliens in it. Maybe it would have worked better if the skull had been some kind of man-made artifact with some kind of relation to Inca or Maya religion rather than the actual skull of some silly alien. That would actually have been cool.
CGI: Too much CGI. I like the practical effects of the old Indy-flicks. They're more earthy and much more charming.
Gophers: Cursed CGI abuse!
Monkeys: I can live with Mutt swinging around like Tarzan, but the monkeys are annoying and unnecessary. Cursed CGI abuse!
No creepy-crawlies: there are scorpions and ants, alright, but they do not have the same effect as the snakes, bugs, and rats of the prequels. Maybe because they're animated rather than somehow based on practical effects.
No Sallah: I like Sallah. I miss Sallah. They could easily have written him into the movie or at least have mentioned him or something.
No Shortround: I'd liked to have seen him too in the movie. In fact, an Indy-ensemble thing would have been cool. Or maybe I'm just too much into nostalgia.
Nuclear blast survival: it looks good and it's funny, but it's too much over the top - even when compares to the usual unrealism of the Indy-flicks.
The skull is no artifact: Indiana Jones is all about finding important, and magical artifacts, but the skull is not an artifact but rather a real alien skull. That is a bit lame I think. And why is it ant-repellent?
Aliens: Did I mention the aliens?

The huh
Capoeira: as a capoeira practitioner, I should be thrilled to see the capoeira moves in the burial grounds scene, but I did go "huh?" because it seems to have been put in there just because it looks cool and so they kind of forgot that it's a urban Brazilian thing and not likely to be encountered in the jungles of Peru.
Gunpowder: I liked the whole gunpowder scene because it shows how much knowledge Indy has, but it's very un-Indy to actually help the minions of evil find what they need. You'd expect him to actually somehow use the gunpowder against the Soviets rather than just helping them.
Opening: The opening itself is very cool but, again, kind of un-Indy in the sense that, normally, Indy-openings refer to some previous adventure, but here, it just starts with Indy having been kidnapped.
Crystal skeletons x 13 = fleshy alien: What's the logic of that?
Death of villain: Exploding head, melting faces = cool! Eaten by crocs = cool! Turning into a skeleton due to super-rapid aging = cool! Disappearing into thin air = huh?
Magnetic aliens: Why are they magnetic? Really, why?

All in all, an entertaining adventure sci-fi film, but not really an Indy-flick. While not disappointed myself (that much at least), I do understand why it disappointed a lot of people who expected a classic Indy-flick. Aliens, ptah!