I just updated Grav to 1.1.1!
It was as simple as clicking the Update Grav Now button and then logging out and in again. Plugins and Themes also automatically updated, and my custom theme, which is derived from the default Antimatter theme, also seems to be ok!
So far, everything seems hunky dory... and this post is a bit of a test. I get an error on the Plugins Admin page as follows:
You are running Grav v1.0.10. You must update to the latest Grav v1.1.x release in order to ensure compatibility. This may require switching to Testing GPM releases in the System configuration.
But, I think this is just a minor issue since the footer of the Admin pages clearly reads Grav v.1.1.1 - Admin v1.1.2.
You can read about the changes in 1.1 at the Grav blog, though most improvements seem to be back-ended and do not affect my experience with Grav.
Updated 20 July: After this post, an update to a couple of Plugins was available. But I kept getting an "Invalid Security Token" trying to update them. Instead of clicking Update All on the Plugins page, I clicked update in the Dashboard and that worked, surprising me! Now, I no longer get the version error above, but do occasionally get the "Invalid Security Token" when saving pages. Hmmm...