The story is well written, genuinely funny, and has an interesting, (if cliched) premise. Big mac, and Prince Blueblood both gain some very good characterization, and the interpretation of Cadence/Candance is intriguing. The OC is quite amusing.
However.. the main 6 are all single dimensional characters in this. Some of these are well done single dimensions, (Rainbow, Pinkie). Some of them are just 'acceptable' in how the author portrays them. (Twilight, Applejack)
Fluttershy, Rarity, and Spike however.. are awful. Rarity only shows up so the author can bash her, Spike is nearly the same, though barely shows up at all, with Twilight making cruel jokes at his expense, and Fluttershy is just.. wrong. So wrong.
This is probadly the best wrote fic that I couldn't finish.