I reckon Edward's description in Ch.3 is the most succinct and effective I can ever remember having read in any novel. From one medium-sized paragraph, nearly half of which is devoted to his skuzzy family, I feel I could recognise him within a couple of minutes of having met him in person for the first time. How does she do this? With a few fairly commonplace nouns and adjectives, perfectly - Oh so perfectly! placed, and especially by double phrases, the second building on its predecessor. "His understanding was good, and his education had given it solid improvement" is one example. These two bounce off each other. He is naturally endowed, and that quality has been developed. "But he was neither fitted by abilities nor disposition..." is another. And what does she skip over, as being the least important feature? What he looks like. "He was not handsome" is the sum total of it.
But what then of Marianne? An "ordinary" novelist would introduce a character, then spend the rest of the novel saying what they said, did and felt. And Jane Austen appears to do this when she introduces Marianne in Ch.1. Again, the salient features of her character are presented as efficiently as only Jane Austen can. But then what does she do? After another nine chapters, for the bulk of which Marianne plays a central part in the story, she suddenly presents us as late as Ch.10 with a physical description, as detailed a one as any in her whole canon, from what I can remember. And how ravishing that description is! When she says, "when, in the common cant of praise, she was called a beautiful girl, truth was less violently outraged than usually happens", we know that no higher praise is possible from someone as reflexively satirical as Jane Austen. I'm certainly in love with her (for pity's sake, don't tell my wife!) And how wonderfully placed this description is! It rams home to us what her initial effect must have been on Willoughby. Only then do we realise that that's why she waited so long to give us this description.
What a delicious woman! I mean Jane - or do I mean Marianne? Who knows?