1st of all, congratulations on completing your first game jam. Making a game within 7 days is an achievement on its own.
There were some some problems-
1. Jump was some times unresponsive
Solution: This is how I implemented jump in my game - youtu.be/j111eKN8sJw
2. Character gets stuck in walls
Solution: instead of using a box collider use some other collider with rounded edges, If you necessarily need it to be in shape of square then use polygon collider instead and slightly round the edges of the collider. Also its a good idea to have less friction on the player
3. Character movement was little slow.
Solution: Here is a video that shows how to make movement snappy : youtu.be/yorTG9at90g
4. Camera moving suddenly.
Solution: I am guessing that either you have put the camera as a child of the player or you have a script that sets the transform of the camera equal to position of a empty game object that is child of the player. The way I would do it is I would have a script on the camera that moves the transform of the camera to the position of a empty game object that is child of the player BUT make it move slowly using the Mathf.lerp function.
Over all great job on the game. It is so much better than my first Jam game :D