my favorite under-the-radar iOS features

So I’ve been on iOS for several weeks now and with a plethora of new features there are a few subtle ones that I’ve really enjoyed. In no particular order;

- You can turn off individual calendars. – Emails are threaded (like gmail conversations)
- And if someone references a date in email (ie “next Thursday”) you can click and make it an appointment that goes right into the calendar application. Truly inspired.
- SMS has a character count
- you can lock the auto rotation, making it 1000% easier to read a document lying down

What about you, what (other than the obvious) is your favorite subtle iOS feature?