I'm loving my 75 so far, works exactly as advertised for me and I've been playing around with tones and settings. Just plugged in paired the Bluetooth connection and logged in on the app, had a couple error messages but they didn't affect anything. Did the flash update to stabilize the Bluetooth connection and everything was fine.
Most of the bugs I see mentioned (like Bluetooth) have already been fixed by software updates. There is only so much testing you can do in beta, so I don't expect software to be perfect as soon as it's released, I just expect it to work. So other than wanting to see a few refinements to the app (like actually being able to browse tones not just search) everything is working 100%