Like the rest of RL Stine's works, it's an utter hack-job that he wrote in under a month. (New Goosebumps were released once a month for 4 years from 1994-1998) As you can imagine, they're repetitive as all hell, and the quality is disastrous.
This one is especially shameless, however, as it's the exact same story as the original "The Haunted Mask", only with minor, incidental changes to the main character and the appearance of the mask. The story itself wasn't frightening, but having to wade through clunky, imbecilic writing, and pointless, space-wasting filler was.
I was definitely a glutton for punishment as a kid.