As someone who was a big fan of the anime show.... It was alright. It was reluctant to watch it, because to me, Slayers ain't Slayers without Lina's familiar companions (Gourry, Zelgadis, Amelia, etc.), but I decided to bite the bullet and give it a try anyway, and I was positively surprised. It was alright. Not as outstandingly amazing as the anime show, but neither particularly bad.
If you want to get into Slayers, maybe start with this instead of the anime show, because this is a prequel to the anime show.
Animation is good (peak 90s animation), voice acting is good, the story is okay, but overall, it's nothing to write home about.