This movie is just silly.
It's clearly dumb fun, but even calling it "fun" may be overselling it somewhat. Masters of the Universe is not a good movie, but at least it's entertaining, despite itself.
The Eternia stuff is obviously where all the money went. The huge sets and complicated costumes are attractive and inventive (it's also a rare movie where our main hero is wearing fewer clothes than the female characters). Sure, this movie is based on a toy line, but these parts look better than they have any right to. I think just about everyone would've loved to have seen a movie completely based in this environment, but that wasn't to be the case.
No, instead, we get to spend most of our time on present-day earth with a couple of teenagers who get mixed up in He-Man and friends' dimension-hopping adventures. The generic small-town sets are such an apparent cost-cutting measure and that does feel annoying, but fortunately, there's not too much time spent on the "what is this strange world we've found ourselves in?" stuff.
Dolph Lundgren, as He-Man, is not nearly as bad of an actor as you'd expect him to be. He actually carries the film pretty well with an innocent nobility. Still, he does seem to be thinking really hard about his acting, although it works. Frank Langella's performance as Skeletor is appropriately hammy. Everyone else is largely interchangeable or forgettable, but you're not watching this movie for the performances.
Moebius is credited as "special designer" on this movie, which is about as vague as you can get, but there does seem to be his touches in terms of set design and styling of the costumes. All that stuff is great. There's just not enough of it.
But there are enough battles (with swords! and lasers!), reasonable PG-rated violence and explosions to keep Masters of the Universe mostly entertaining. But except for the Eternia stuff, it's also mostly forgettable.