For movement:
I think it suffers from the delayed movement. In a game about precise control, it doesn't feel too good when the inputs are all delayed, and makes it feel more like it's the games fault you die, rather than a skill issue.
If you tell us its on ice, or skates or something, it's more justifiable, but as is, it just feels clunky, and like you did it, just cause momentum sounded cool.
For the shield:
It might pay to make the shield aim relative to the player position, instead of looking toward the mouse cursor. Just so you can always have faith in flicking your mouse in a direction to block a shot, rather than having to move your mouse to the right spot.
In my own opinion, I think that would feel more responsive and engaging.
Perhaps you could make it a setting, if you personally prefer the way it's done now.
Other than those, I think for what it is, it's solid, and fits the theme.