Like what everyone else has said, Dimitrov has great potential. However his footwork and shot selection is nowhere near as good as Federer which is essential to Federer's game. Also sometimes he hits shots that are too flashy during key points of the match, like those sliding splits when he's outwide.
Highlights of his match with Almagro from the AO, look how far he is from the baseline when he's defending and also how he hits regular rally shots with not enough angles.
http://www.youtube.com/watch?v=WyrGxwHEXcg
Compared to Federer's shot selection against Del Potro
http://www.youtube.com/watch?v=EqoRGR4aMS8
I only see him going up to Kohlschriber's ranking at this rate.