some comments - this is not intended to be harsh but reading it seems like it is. its not meant to be.
start and back buttons a little small.
shadow around bottom white edge is incorrect - should fade to darker.
could possibly add reflections to the buttons - give them a shiny effect.
you missed the button labels.
the sticks/pads colour seems to be a little off - not sure exactly what is wrong just that something is.
did you copy it or do this from memory? i feel this is from memory and if so this is very good work nonetheless so don't take the critiscism hard. even if its a copy its still good.
i also have to agree - not the most interesting of objects but a decent one to get small details right so when you move onto bigger stuff you can handle it better.