I have the exomount too, it's nicely designed but because it's made of plastic, not reinforced, it tends to judder around if used with a large screen smartphone phone like the S2 and up. It's not a problem unless you're using satnav and trying to read a direction as the juddering becomes an annoyance.
I can agree with the juddering. I mount mine in a way that the base of the gripping claw/device is anchored against the dash or something else, just to stop the shakes.
When mounted for GPS use anyway.