Simple question, is TAS worth watching?
The animation is not that great by today's standards. If you grew up on reruns like I did, and hadn't seen it in a long time, it definitely is worth seeing.
If you never saw it, it really depends on how much of a fan of TOS you are, and if you are a completest, or not. It technically isn't canon, so if you miss it, you miss nothing. It is a mixed bag, though, and I will put it this way: the best episode of TAS is about as good as a medium episode of TOS. I am going to say you should see at least an episode, and decide for yourself, if you want to continue.
I think if they ever took the audio tracks of the actors lines, and reworked it to a modern CGI animation, and updated the sound FX, it would be a lot better. But this will never happen.