The interlock system is user-friendly and pretty easy to master while being not too annoying while driving down the highway. However, and this may be from poor installation, I was forced to endure six months with the thing in my car and the last three required me to pull it in for a calibration only to pull it back home and let it sit for the next month because by that time I had gone through three batteries on my car in the SmartStart installer in my area refused any and all culpability. Let me be clear, my car physically would not start and multiple brand new batteries went on the car, failed to start it, and came off with less than 30% charge. My car has a push button start and anytime I would get a charged battery on it I would get to the point where I was ready to push the button and start my car and everything would go dead. Once I finally was able to get it removed and get the battery replaced (again), I was able to start my bagel for the first time in three months.Yes I understand that I was required to have this device because of a DWI but that is not justification for my wife, two children, and myself to be without the use of a several thousand dollar investment for a quarter of the year.