I couldn't see this one on the first page, although I may have missed it.
This will be extremely minor point to some, but it's very useful for me. My iPhone is my personal phone & I have another one, typically, for work use. Occasionally, however, I will read some news article or something & want to email it to my work address.
This is fine until I have the situation where I have changed jobs and I could find no way within previous versions of iOS to remove my old works email address from the auto complete list.
This resulted in me having to be very careful to select the correct one avoiding any finger trouble.
Anyway, you are now given the option to remove an address from this "recent" list, which will save me time & remove the need for me to have the manual dexterity of a surgeon when sending an email
EDIT: I've added in a picture to show the interface. It only works when the email address to be removed is not included within one of your iPhone contacts, which would make sense.