What I found to dislike...

(Spoilers so be careful) I like Louis Malle, and I liked this first film of his...but the fact that The French Film Critics gave it their highest award that year and everyone involved and the "Film World" continue to believe it's some masterwork is laughable. There were far too many very poorly executed and poorly written scenes, as well as just a lot of dumb stuff. The Best films avoid this...this film did not.
For example...

1) No way the Grappling hook would have ever fallen off the railing and landed on the stairs of the building. It simply would not have happened. How? How is it possible to fall by itself?

2) No one just leaves their car running with the keys in it, especially knowing that their errand will take them at minimum 10 minutes to get to the very top of a building.

3) Malle errs greatly when he has the "kids" drive past Jeanne Moreau and gives us her perspective...in which she sees - as does the audience - that it is NOT her lover driving. If Malle had executed this shot properly then we never would have seen the face of the male driver, but we do - as the audience - and so must she, since it is her perspective. Again, if I can see it's not her lover Julien...then why can't she??

4) The kids smash into the back of the german couples car, obviously on purpose and after following them...and the German just laughs it off. Idiotic. This was handled poorly. Laughable that the German would not realize it was on purpose and not some thing done accidentally.

5) The shooting of the German couple was inept. Very, very, very poorly staged and executed. Laughable for a "masterwork".

6) The scene of the kids deciding to kill themselves was again, inept, poorly written and horribly acted. Laughable. The only good thing to come from that scene was that they didn't die...oh and the girl did have an extra key.

7) There's a really bad shot of Julien clearly just hanging on the rope - like a close up of his "fear" - intercut with the elevator descending towards the bottom. Horrible. We see him dangling in the previous shot with the elevator going down and then we see this static shot of him hanging there...as if we're supposed to believe he's going down. Clearly we can see he is not.

8) What the heck was the point of that stupid drunk friend a second time, putting his head on her shoulder and then that woman asking for a light and having the camera raise with her and stay on her for like 5 seconds to end the scene in the police station?!! Was that woman someone's girlfriend promised her acting union card? It was stupid in the first place to stage it so that the drunk jerk puts his head on her shoulder the first time...but for him to do it a second and final third time and then pan up to that woman to end the scene...was just dumb.

Yeah, it was a decent film. Lino Ventura and Jeanne and Maurice and Miles were all excellent. But - and here's where the knives come out, right, ha ha - if I had directed this film, I would be very embarrassed by many of the stupidly staged and written scenes that remain in this film.