I've just loaded this on, and so far so good.
You cannot however downgrade, and you CANNOT use your old configuration from either 1.16 FW or 1.15. It's best to start from scratch anyway.
Again, it's a beta firmware, and it seems good so far. They've added the Advanced DNS service, which is currently on the DIR-655, and the CATCHPA authentication to login to the router. I disabled both however.
Just to note, BEFORE and AFTER flashing, you SHOULD clear the NVRAM by doing a 90 second reset, in which you hold down the reset button. After the first 30 seconds, remove power, and keep it out. Another 30 seconds should pass, and you should plug the router back in. And continue holding the reset without letting go for the last 30 seconds.
DO NOT under ANY circumstances flash over wireless, as there is a chance you can brick your router due to corrupted firmware and dropped packets through the radio waves.
AND! Last but not least, for those of you who use Shareport, PLEASE reinstall the software to regain function of your NAS devices, etc.
I have so far tested my games associated with Blizzard Entertainment..and it seems okay. Still a few spikes, but it seems better.