I just got done watching Indiana Jones and the Kingdom of the Crystal Skull. What a huge disappointment! It was easily the worst of the 4 movies. Even worse than Temple of Doom, if you can believe that.
There was very little of the trademark humor, and what there was seemed very forced.
The acting seemed stiff. The "fun" of the movie just wasn't there. Combine all that with a crappy story and you've got a bad movie.