Updated my m3800 to 16.04 yesterday and ran into a few problems.
My trackpad behavior is really flaky now, I can tap lightly on the trackpad to 'click' but I can't actually press hard on the trackpad to click anything. Two-finger scrolling doesn't work any more. And the "ignore trackpad touches while typing" appears to have gone away.
Bluetooth got flaky. Specifically, the Jaybird X2 headset that I had to hack a workaround to get working in 15.10 is no longer working on 16.04 despite following the same setup steps.
Everything else seems fine, graphics, thunderbolt, usb, wifi, etc are all working okay, but the trackpad issues are starting to really irritate me, so if anyone has found workarounds I'd love to hear them!