The way his voice goes up at the end of his "I should kill you with my BARE HANDS!!!" is pretty hilarious. Seriously, it's quite an accomplishment to overact more than Williams Shatner.
The transition from Kirk to Garth's true form during the temper tantrum is interesting. It's one of Shatner's weakest performances, and he seems to be just going through the motions, rather embarrassingly. Then suddenly there's Inhat, pounding the floor full of fury.