Not bad, for what it is.

For a dimension mod this simple, Splintered Floorboards is a surprisingly unique and well-realized concept.
That said, for a simple mod, I also encountered a ton of bugs, like the dimension's mobs spawning in the overworld, and a crash when mousing over certain mod items and pressing shift.
To reflect the mod creator's wishes, I'll keep discussion of what the mod actually does to a spoiler tag:
Create a Splinter and Bone, light a wooden portal, and go to a dimension that looks similar to the overworld, but for a yellow fog that prevents you from seeing far, and the fact that all blocks have been replaces with various types of wooden planks. Plank trees, plank caves, etc. Wooden mannequins carrying unique weapons stalk the landscape, they look just like you, but wood. As you search around, you can find houses built by other visitors, filled with signs that ask questions like "is this all there is? wood forever?" boarded-up sections of house, and even a door to mid-air ominously labeled "jump." It's a really unique and interesting atmosphere, and I feel like if there was a bit more to do in the dimension, (I'd love to see an equivalent to ores underground that require higher levels of axe,) and the mod worked a little better, this would actually be a really cool little dimension mod.