Since ATT has decided to be a total **** to WP8 customers, I would flash my 920, but I have it set up just the way I like it, and don't want to risk voiding my warranty I'm pissed though, that moto X customers got their update today only 2 weeks after it was made available. I seriously can't figure out what's taking them this long.
By mentioning Amber I assume it's a Nokia Lumia. What issues are you talking about. If I were you then I would update to GDR2 and Amber, they solve more issues than they create anyway.
I'm enjoying glance, data sense, smart cam,etc for my 620(post amber update). I don't really have any issue post amber update. It seems faster especially when i open up setting tile.
I think Data Sense is an excellent addition. My phone (Lumia 620) updated fine today to Amber. Glance I'm not really bothered with, but my 'Other' storage has not reduced at all since updating. I was sort of hoping it would reduce but the phone seems to be holding steady at 1.25Gb free space.
One other thing I've noticed is that the battery life seems to have reduced by a few hours since the installation of Amber. This is via the battery life reading from 'Settings'.
The only major issues with GDR2 I've heard of have been on HTC devices. If you're talking about Amber, it's safe to assume you're using a Nokia device, so I think you'll be fine.