Don't look a gift horse in the mouth.
Neither Lucas nor Spielberg are in need of popularity, and certainly not money, which is the main reason for any sequel. It seems that Lucas will manage to stretch the Star Wars product forever, and Spielberg... well, he didn't get the nickname of Hollywood's King Midas for nothing. From the very beginning, it was clear that “Indy 4” would be a present from them to the fans. Take it as what it is, a present. Deeper insights will probably ruin your experience.
Yes, everything is there: they have made sure that all the elements common to other films of the series are present: punching fights, innumerable chases, humour, the charismatic sidekick, bugs and reptiles, dark catacombs,... Just hearing another character calling Harrison Ford “Dr. Jones”, or having the main theme on the big screen again after such a long wait makes it all worth it.
However, certain aspects of the film deviate from the atmosphere present in the previous three films. A few far-fetched situations, even for Indiana Jones, somehow manage to ruin the credibility of all other things, humanly impossible and still believable, that the character has done in previous films (Indy is not 007!). Some scenes, like the very first one, seem to be unnecessary long and reduce the pace of the film and makes it harder for the spectator to get into the story. And of course, there is what Indy's new adventure is about: it seems to fit perfectly with the others when, suddenly... well, we are taken in a direction where we don't want to go! (you'd better watch and judge for yourself).
Something similar happens with the load of visual effects. Just as we saw in Star Wars, the urge is felt, it seems, of making use and overuse of the new technologies where they hadn't been needed before. The result, rather than Indy, feels more like watching its putative relative, The Mummy. Actors don't seem to get along with the new technologies either and so sometimes they just stand there looking around, unable to interact with the digital part of the set, fact which contributes to a couple of unsuccessful scenes.
One would think that after managing to go on without Sean Connery in the project quite believably, Spielberg would be able to rely on the rest of the cast (Karen Allen, from the first film, among them) to put strong empathetic characters into play, just as he usually does. Sadly, there are quite a few occasions in which the characters either don't seem to know what to say -or how- or they just come into the scene for no reason, and leave as clumsily. The combination of the relationship between the characters and the high level of adventure is not handled as successfully as it would have been expected, and we are left with a certain thirst for more personal moments and less action (and explanations!): moments to show us more of this new, older Indiana Jones, which is taking more and more after his father, or to enjoy Indy's reunion with his very first film girl.
Let's hope this is a momentary lapse for Spielberg's otherwise excellent craft, and that he is not finally listening to Lucas' directing suggestions.