The idea of the rough mix, is not to listen to it as an overall final product.  Rather it is mainly designed for you to listen to the song, and analyze the parts.  Are your parts played well?  Are you happy with the sound of the instruments?  Does everyone seem to be playing well together?  While you are listening, you can make notes about what you hear, and write down suggestions for the mix down session.  I.E.  Move guitars to the left, add reverb to vocals, make cymbals brighter, etc...  We'll take your notes and compare them to ours so that we have a 'recipe' of sorts for the mix session.  

It's suggested that you wait until the next day before listening to the rough mix.  This gives your ears time to rest, as well as the rest of your body.  It's hard to be objective when you are tired.