Much better than I was expecting, and just a really solid movie in general. Gal Gadot is the first actor in the DCEU (excluding suicide squad since I haven't seen that) that really embodied their characters. They kept away from introducing a lot of other characters to set up future movies, and focussed on giving Wonder Woman an engaging character arc. The World War I setting was perfect for the movie, and I love how it actually felt like a war compared to the sort of gee willickers version of war from The First Avenger.
The main complaint I would have is the pacing. The movie gets really good when Diana actually gets into the war, but prior to that it's a bit meh. Not bad, but they spend a little too much time at her home island and in London, and the fish out of water comedy begins to wear thins. They're still introducing characters about an hour into the movie, which was in general a bit too long. The villains are also kind of weak. It makes sense that we didn't really get to know the main villain all that much, but the secondary foes have limited motivation beyond "they're really mean".
The most important thing though is that Wonder Woman has something that no other DC movies have had. Likeabe characters. Superman and Batman are unbearably moody and gloomy. Wonder Woman and her supporting cast actually display an array of emotions and even smile once in a while. Imagine that. It's not as quippy or funny as Marvel's stuff, but that's fine. It doesn't have to be as humorous, it just can't be so aggressively glum. There needs to be a reason we actually want to see that world saved.
To do the inevitable comparison to Marvel movies, it would be about middle of the pack. I certainly liked it better than the weaker entries (Thor, Iron Man sequels, Captain America), but I don't think it was as good as the better entries. To compare it with Guardians 2 (just cause that's still fresh in my mind), I was more engaged during Wonder Woman's biggest moments, but I was also bored during some stretches. Guardians of the Galaxies highs weren't as high, but I was interested throughout the whole thing.
From a story POV, I enjoyed BvS Extended Version more than I did Wonder Woman.
:::zips up flame retardant jumpsuit:::
It's ok. Some people enjoy having someone shit in their mouth more than a delicious bowl of ice cream. There's room for all kinds on this crazy blue marble.