Overall I think the negative reviews are going off on nothing.
True, he-man doesn't come in each episode stop Skeletor and tell you a life lesson but it can't be when it's targeted at an adult audience.
This more answers questions you probably asked yourself about he-man/Adam's biggest weaknesses and what if Skeletor wasn't a complete failure, what would happen.
The two dings I'm going to do here to go to 4 stars are not spoilers are this point. Race swapping established characters is weird, strong characters of any background should exist in their own right.
Additionally having only 5 episodes and a huge cliff hanger sucks. I am assuming that as more episodes are added He-man will be the main hero but there isn't a huge reason not to.