I didn't really see ANY character evolution.
Evolution (noun): the gradual development of something, esp. from a simple to a more complex form.
That's the second definition of evolution in my online dictionary. If anything, I found that SMeyer's obsession with their 'happy ending' ended up shoving aside the character's development. I thought they became *less* complex by the end of it.
Jacob was no longer the broody/happy/immature/understanding guy. He was just the person who was in love. Imprinting made them LESS evolved. Instead of giving them multiple reasons for life, it gave them a single reason to live, a single reason to continue to adapt and reproduce, etc. etc.
Bella's transformation made her less complex, because she was no longer a confusing human. She didn't even whine as much (although, towards the end of it, she definitely got her whining quota back).
Edward was never very complex. His only problem seemed to be his obsession with keeping Bella safe from himself. By the time she turned into a vampire, he had no complexity at all. He was completely lost in the train-ride to the happy ending.
I thought Rosalie became complex in Eclipse, but by Breaking Dawn, she had lost all of that in her selfish desire to have a baby, even if it was not her own. I definitely don't think less of her for it— I really do like Rosalie, especially in the first two books— but characters can (and are MEANT to) have multiple motives (I hate throwing JKR into this, but think of Snape).
The characters remained very flat, and the ones that were not flat in the first place, became cardboard. It was a disappointing 'evolution' for me.