I haven’t had any issues since I set mine up in August. I have periodically tested and everything was fine. We did have a phantom alarm at midnight a month or two back and the system worked exactly as designed. The smoke alarms sounded and all of the lights in the house came on. My wife was able to get our 1 year old son quickly and I was able to check the house for fire. Luckily, it was a false alarm but the system worked well.
My only wish would be that the Schlage sensor reported battery level. I periodically have to check to make sure it is still reporting in to the Smart Things hub.