TAS was great for what it was. Animation at the time was super cheap and outsourced, so you can't really put them blame on them for something that was pretty standard at the time.
One of the neat things about Star Trek: The Animated Series is that they were able to have crew members and aliens that were more than just humans with a couple of prosthetics. Aside from the Horta, and a couple glowing space things, basically every alien in The Original Series was a quickly painted extra.
You'd be hard pressed to find someone who says TAS was their favorite Trek, but it's probably in my top 4 Trek series.