There are a few inventive moments, a few nods to other movies but the rest is either a tired retread or just too implausible to the point that you cannot suspend disbelief.
The early films have a frenetic energy about them, and Raiders set the bar so much higher than any other movie before it. In fact the Indy II and Indy III were always going to be viewed poorly against the original, even though they were great films in their own right.
As Roger Ebert put it in his write up of Last Crusade 19 years ago:
But there was no way for Spielberg to top himself, and perhaps it is just as well that "Last Crusade" will indeed be Indy's last film. It would be too sad to see the series grow old and thin, like the James Bond movies.
Also missing is the dry humour from earlier movies.
But it is the energy that this lacks most of all. In the script, in the imagination, in the wonderment and in the character.
Ebert was right. I am reminded of Roger Moore in A View To A Kill. The tiredness of both the series and the leading man.