Every reader will have different preferences. A lot depends on the intent of the writer, of course, and how they want to "work" the character's physical appearance with or against how the character behaves. Too often writer's fall into the stereotyping trap, i.e. handsome and beautiful people make good sex partners, sloppy/slobby people can't be detail-oriented, etc. Going against type can broaden the scope of both the character and the reader's perception. Also in the case of reader identification, more vague characters will work toy our advantage. If the heroine is blonde, skinny, and solidly British, it'll be harder for, say, a darker-skinned, dark haired, Rubenesque Greek woman to identify with her. In which case, you have to dig into the "universal" characteristics to pull the reader inside the character.