The kick is, to my belief, one of the most underrated upgrades in the game. People mostly use it for the 'Get Up' perk, which allows you to counter Spidertron 5000 and 6000 extremely easily. I beg to differ.
The Kick. A very useful ability to have in your arsenal (no, not just for kicking people into sawblades).
The main thing that I utilize with the kick is its flip. The precise hitboxes in this game means you can flip away from arrows, dodge sword attacks and even get away from Spidertron shrapnel whilst kicking enemies into it themselves. The main thing about the flip is that you can do all of this - and more - with just one kick!
In addition to being able to dodge, you will also be knocking an enemy out. This will help your thinking, as you will not have to concentrate on as many robots. You can also knock enemies into saws, leaving for a natural kill. Another thing that is possible is knocking an enemy into another robot's attack.
Here's a quick example:
You are in a really bad situation in the Titanium tier. A Mark II jetpack bot is speeding towards you, an arrow is headed straight for you, and a Spidertron 6000 bomb is right in front of you. There is also a Mark IIII swordsman standing near the bomb, in front of you. You kick the Mark IIII swordsman, knocking him into the bomb. Mid-kick, a jetpack bot slides under you, failing a side cut. Under your body arch, an arrow directly hits him in the head, killing the jetpack bot. Then, the Mark IIII swordsman gets up and starts rolling away from the bomb - but it is too late. The bomb explodes, killing the Mark IIII swordsman. You then jetpack towards the Mark IIII archer, killing the remaining robot and ending the round.
You've done it.
You've cleared Round 49, your new personal best (without hacks).
So is the Kick overpowered?
Well, if you use it right - yes, indeed it is overpowered.4
[EDIT]
Forgot to mention - you can kick people in a 360 degree area around you. The kick always flips away from the enemy.
This can be used to peform some amazing acrobatics.