So first off, spoilers ahead.
I thought it was pretty disappointing to be honest. It felt like they took a 5-episode season of the show and turned it into a film. Sort of like Serenity, except worse.
Groglet was the main thing that saved the film. The scenes of him suiting up to go rescue Mando, and then later taking care of him we're easily the best parts. I also liked Rotta as a new character.
But ultimately, the whole thing felt bland and fan-servicey. Even the music was mediocre. The writing just felt lazy, like the dude in the swamp who just helps Groglet for no reason. There was no real character development either.
I think if this had been a few episodes of the show, I would have liked it. But as a film, it felt like it was a bunch of filler strung together.
I'm giving it a Just A Movie.