So this is a nice change of events for people upset about the carrier branding and AT&T boot animation on the AT&T Nexus 6. I was. It went against what I love about the Nexus line. It didn't feel like a true Nexus. Also, if you're worried about root, unlockable bootloader and installing a custom recovery, don't be. I received my AT&T version today and instantly went to work.
Before I ever installed the SIM I unlocked the bootloader, then rooted and installed TWRP.
About that AT&T logo on the back. Gone too. Sharp scissors or knife can easily scratch that off. Now the back is clean and you can't tell there was ever a logo there.
(not my picture...courtesy of XDA)
The AT&T boot animation is gone now too. Open a file manager, OEM (mount r/w) > media. Rename the boot animation to whatever you want. Gone.
Also, because I did the root, unlock and custom recovery without a SIM card, none of the AT&T bloat downloaded to my Nexus. Google made the phones capable of downloading the usual unremovable bloat when you activated with the respective SIM card to appease carriers. This time the bloat was going to be removable because they would be part of the ROM partition (a nice gesture, no doubt). My method circumvented having to delete those apps.
Nice, huh?
If the $650 price scared you off from buying the Play Store edition, you can still have the genuine Nexus experience on contract.