See, to me, the vibration is perfect! I was using a ZWatch for a while and that thing sounded like an industrial vibration unit was strapped to my arm. My boss always knew when something came in, so I typically didn't bother with the vibration feature except for wake-up alarms.
With this, I get two very quick buzzes and it's silent. I've set it so the notification doesn't force the display to turn on so I can be more discreet in seeing my notifications.
I see nothing wrong with the vibration.
However, if others require more, then hopefully there's something that can be done to address it.