Yes - you do get a nice discount, you get white towels, and you are able to reserve the beach/pool side beds.  We like to think the already excellent service is a tad better too.
There is no Premier dining or drinks - all alcohol is top shelf if you call it and the food is wonderful.  All your normal 25% off discounts apply for wine, food & shopping to.
6-night stay at 
Desire   entitles you to:
*Lobster or Black Angus dinner
*2 25 minute massages
*Wednesday wine, fruit, candles
*Round Trip transportation free
Email Premier and they will send you a checklist for all the resorts on what Premier gives you.