It sounds like the dev was very satisfied with parallax, but I don't recall ever using it. I think it just felt weird after already getting used to the default.
It also degrades the visual quality of the sprites by not rendering them in 1 to 1 scale. From a modern standpoint where a bit of 3D does not have a wow factor I think it actually looks worse.
I also found that it was "closer" in and I couldn't see as many of the enemies. For casting, this was an issue.
It did give a sense of 3D back then when the character is moving fast with a lot of obstruction objects (walls and trees) passing by. Some rendering also gave better lightning effects AFAIR.
It was also nicer on the time-blurry CRTs of the era. The previous frame would still be a ghost of a memory covering a lot of flaws.