The writing style of The Wee Free Men follows a pretty typical narrative, but gets decidedly whimsical when we're confronted with the inhabitants (or former inhabitants) of Fairyland. After all, the pictsies have their own dialect:
"Crivens! It's a'verra well sayin' 'find the hag,' but what should we be lookin' for, can ye tell me that? All these bigjobs look just the same tae me!" (3.35)
But the rest of the writing in the book is pretty straightforward. Once you get used to what the pictsies are saying, their dialect brings a playful element into the book that's fun to read.