I enjoyed this episode, because it introduces new, interesting inhabitants of Third Earth, and is full of action.
The Micrits are really interesing people, but I'm not sure if they were ever used again in later episodes. Somehow they are able to make strong, glowing strands of Thundranium that are able to hold Lion-O down and weaken him.
The battle in Cat's Lair is pretty exciting. The Thundercats are able to hold their ground, but they don't gain any at all until Lion-O arrives. Wilykit exhibits that strange forward-spinning maneuver she possesses in this episode. Animation is quite superb as the Mutants are driven out of Cat's Lair. Vultureman and Jackalman's expressions are really funny.
All-around a great episode with non-stop action and suspense. And the writers even throw in a moral: be kind to your neighbors.