I did enjoy the movie overall, just to start. There definitely were a few parts that I thought were too far fetched, even for an Indiana Jones movie. But those parts were a small portion of the movie.
I don't want to give any spoilers for those that haven't seen it yet. But, I would say about 95% of the movie is classic Indiana Jones, and even feels nostalgic. The other 5% are maybe too much over the top, but in no way ruin the movie. To me its not the unbelievability, it more the style of the unbelievability doesn't fit other Indiana Jones movies....
The true test to me will be how everyone feels a few years down the road after seeing the movie multiple times. Will the things that seem over the top suddenly not seem as such? I would rank this movie as the 3rd best Indiana Jones, with Temple of Doom pulling up into last place.
Definitely see it, and don't let the few over the top moments ruin an otherwise classic Indiana Jones movie.