I am of similar mind to Aussiegirl and Mad Lews. I will often provide a general description - hair color and length, eye color and maybe a general description of form. The only time I can recall going into details is when it particularly important. If a person in my story has a drastic change or a particular oddity (as Lex described), otherwise, I leave it rather vague. Something along the lines of "She as all curves with a hint of dancer in her legs" or if I want a particular image I might even throw in something like "she looked like a Frazetta painting come to life". That way, if my readers know who Frazetta (or look him up) is they can get a good vision of what is in my mind. Still, I leave it plenty vague and allow my readers to make up their own vision of "She was beautiful".

I admit that this is not just due to taste but because of the amazing commonality so many erotic authors have of giving a 44DD bust to women and a 10 inch cock to the man. Who really needs that unless it is entirely integral?