Excellent show. Unlike the 80's cartoon, this show has a cohesive story. It's only 5 episodes into a 10 episode 1st season.
If you're looking for Adam to say "I have the power" a few times and punch a bunch of henchmen buffoons, for 30 minute episodes, then you'll be disappointed. Only to have different stories every episode, then you'll be disappointed. If you are looking for a good story, then look no further.
Also, this show is entitled "Masters of the Universe", not "He-Man and the Masters of the Universe", like the 80s show was. Which means, it's ok to have a bit more focus on the non He-Man characters, because that is how a good story is built. For example, "Game of Thrones" would have been a hell of a lot less exciting if it only focused on Jon Snow.
Lastly, Teela is a warrior, who regularly fights men who make Dwayne Johnson look wish he worked out more, so some muscle definition is completely natural. Look no further than the UFC women's division, for reference.
This is a great show, and I'm looking forward to seeing the final 5 episodes, of this season.