Wonder Woman was everything I want in a movie about heroes. In terms of comparison to Marvel movies, I'd put it as above average. Certainly, better than most of the individual hero movies.
But, reviewing it on its own merits, I loved the film. The casting could not have been better, especially Gal Gadot. It was good to see a hero smile an actual joyful smile.
Some spoiler talk
Wonder Woman came across as a noble hero, with an appreciation of humanity, even if she didn't fully understand them. It was awesome to see her motivation go from ending a threat to saving the world. She transformed from being a sword to a shield.
At first, I didn't think they had a good reason for going with WWI instead of the comic canonical WWII, but after watching the movie, it made sense. The world at the time of WWI was very different than the one today, definitely moreso than WWII. Scenes like Diana in the meeting room with men, really work with the mores of that time. Also, the international aspect of her allies (as well as other soldiers in the background) work really well for the Western Front.