Ketar was released in January 2016. I obtained the set on December 31. And it somehow exceeded my worst expectations.
First off, the set has too many colors. It has brown, tan, and Dark Grey, none of which are present on Pohatu, which means it's not even good in unity. No two parts of this set are the same colors. You've got the grey tail that comes in brown for the feet, a grey neck that comes in trans-green... for once, the red and blue pins don't look out of place because the set has every other color of the rainbow.
Second, this is the first Bionicle scorpion set that can't sting. I'd forgive this if it had a good function, but it doesn't.
Let's mention the function. I got Uxar the same day as Ketar, and Uxar had a blue friction pin holding the function in place. Ketar does not. His function flops around uselessly, and if you use it to much his arms fall off. In addition, his head gets in the way of the function, meaning he has to constantly bow his head in shame.
I'd be willing to partially forgive all of that if the unity was good, but it isn't. Pohatu gets arms and legs splayed out everywhere and a tail.
All of this adds up to Ketar being the worst BIONICLE set ever. Yes, worse than Solek. Solek had poseability, wasn't floppy, and had an actual color scheme -- a boring one, but it is consistent.
So, let's sum up the set.
terrible color scheme
Red and blue pins
hard to pose.
Arms come off too easily
Silver head clashed with gold mask and looks downright ugly.
Ketar has a dark tan Vorox piece, brown feet, and two swords. This is the only good thing about this set, and the only reason to buy it.