I got the OTA via the Beta Program on my backup N6, and I've been surprised at how... normal my experience has been. The AC app crashed once when I tried to switch from News to Forums the first time I opened it, but it's been fine ever since. YouTube and Souncloud are both working fine. No problems browsing with Chrome or working in Gmail. I didn't get any calls while I had my T-Mobile SIM in (and I didn't feel like making any either), but WiFi Calling showed up in the notification shade eventually after a restart, which was nice to see.
Split screen seems to be working well in both landscape and portrait, too, and I'm liking the System UI options a lot. Yeah, I wouldn't feel comfortable installing this early release on a daily driver since there's no reason to expect it to be stable or reliable, but it's been feeling (maybe deceptively) pretty stable for the past three hours of playtime.