My feedback based on a few minutes of playing:

1. Blocks falling: Yes, I think you should lean into this, especially if the player can cause them to fall on enemies.
2. Weapons felt a little weak: this game feels like it should play like a fast paced shooter/platformer, but I feel like enemies just won't die fast enough for that. Also if a player can get up into the face of a machine gunner without dying I think they should be rewarded by being able to quickly destroy the gunner.
3. I'm still not entirely sure where the machine gun pickup is, I assume it's with the machine gunner behind the sandbags. Maybe make pickups more noticeable against other objects? I had no idea I picked one up (maybe needs an audio cue?).
4. After reaching the end of the level behind the sand bag guy there's a wall, it didn't do anything so I assumed that was the end of the game.
5. Is the character always supposed to be pointing the gun down when not actively aiming? I feel like this shouldn't be the case.
6.  User editable key bindings will be a big deal, I guessed at the controls since the ones listed don't match with my controller (Button 1, 3, R2? I'm using a 360 controller, ended up mapping to Y and A).

Let me know if you need any clarification on my above points. This kind of game isn't the kind I usually seek out to play but I've played similar. Good luck!