Meh.
First, I congratulate you on having the patience to make a medley.
Also, I congratulate you on using that sound for Bowser's roar (I assume), but only the first time. afterwards, it becomes repetitive and annoying.
The Instruments: Harsh.
The Epicness: midway.
The Medleyness: Actually, This was probably the best feature. It flows, and I can tell you actually thought about it.
Overall... 3/5
ALSO: YAY! 1st Review!