I doubt there are any Indy Fans who haven't seen the film yet, but just in case...you have been warned!
I'll leave film reviews to people who are better at them if they want to do one, but I'll focus on the introduction of a new dynamic to the Indy films, which I'm afraid didn't work very well for me or most of the people I've spoken to about it. This is the introduction of aliens to the plotline, which has neve featured anything of the kind before.
Don't get me wrong, the film is fantastic and well worth seeing. It has caught the spirit of the original trilogy and brought the characters back without spoiling the franchise by "modernising" it or leaving it too far in the past - which is quite a feat considering the slew of not so good fourth parters that have been recently, not many of them hit the mark, but this film does and is a delight to watch.
But while totally enjoyable the plot of aliens landing and creating these crystal skulls is a bit implausible and not very true to the originals I thought. The original trilogy concerned itself with religious artifacts such as the holy grail and the ark of the covenant and the consequences for obtaining such items if sought for the wrong reason. While the film sticks to the choice and consequence formula of the others the artifact is no longer an ancient religious relic but something altogether different, which detracts from the film somewhat.
While Crystal Skulls are a real thing (the above picture is not from the film) and therefore valid subject matter I didn't quite like where they took it in the end. That is, to have a group of thirteen crystal skeletons inside a spaceship inside a temple which can move between dimensions was brought on too quickly and with not enough explanation to be absorbed by the viewer. One has to ask if the beings are so powerful, how did one of them get it's head nicked in the first place, and surely the advantage to having thirteen bodies would be that one of the others could go and retrieve it?!
If it had maybe been an alien artifact or the remains of a dead alien I might have believed it. But despite it tying in with the time period and the Roswell crash and that I still can't see it as part of Indy. But nonetheless the film is a great success and is not let down by the alien premise. I guess we'll just have to accept aliens as part of Indy's world now - which I think I can just about live with.