I think Amber improved battery life for my 920 too. Right now I have 24 hrs of stand by with 39% left. I have wireless on, data connection off, glance on. Yesterday I drove for 4 hours and had 3G and Bluetooth on during the whole time. I also checked my email, browsed the web for 1 hour, checked the WPCentral app and some other apps a few times.
However a couple of days ago I was getting massive battery drain and I began to investigate the possible causes. I uninstalled Skype, Glance Background Beta and some other apps to no avail. The battery drain would continue. Then I remembered someone posted here that sometimes your email account can get stuck and cause massive battery drain. I deleted my Gmail account, added it back again, set it to check every 2 hours and my battery life has seen a major improvement ever since.
My advice to you if you have sudden battery drain: delete and add back your email amount. It only takes a couple of minutes and can lead to a major improvement in battery life