I'm on AT&T and definitely have a stable connection at this point (still on the build from last night).
But, I had data disabled on my mobile connection. I enabled data and boom, all of a sudden my signal dropped out and flickered on and off like some people describe.
I'd suggest anyone experiencing a problem where the signal goes on and off try disabling mobile data, and see if that fixes the issue with the cell signal. After I disabled mobile data again, my solid cell signal came back. I can repeat this issue easily, enabling/disabling mobile data kicks my cell signal on and off.
So, other than that issue with what looks like the mobile data, everything else works great so far.
Also, the default APN is the one labeled ATT Phone, but that worked fine for me on my 3G microcell. I switched the default to ATT LTE, and that works too, hope this helps.
Someone asked about getting radio logs, I use lumberjack, but you can use pretty much any good log program or even a terminal or adb if you prefer.
EDIT: Alright, I added a radio log snapshot just after I tried enabling data to trigger the cell signal kicking out, and then disabling data to get a stable signal. Hopefully, there's some useful info there. If there's any other logs you need, just let me know.
