The Good: You appear to understand the basics of sound and graphic replacement, as well as floor over floors.
The Bad: Your level design is abominable. Your sky glitches at times. The music is off-key, and doesn't fit. Water kills you. The level is simply a box with platforms in it. You're creating a level pack that isn't fun.
The Solution: Go read Level Design 101 on the wiki, and read it thoroughly. Compare your level design to that of the main game and Mystic Realm.