I find the vibration to be too weak and I miss notifications, this isn't exclusive to the Quartz I've experienced this on several watches. Thankfully there is an app you can install to help with this problem. It's called Feel the Wear and it allows you to change the vibration globally or only for specific apps. I like to change mine to two long vibrations to make sure I really feel it when I get a new notification. You can also set custom sounds that will play through the watch for specific apps.