I recently purchased a Cheetah GPSMirror and I am quite impressed with it's satellite acquistion times. It's very speedy, and that's even when my vehicle is parked inside my garage.
In comparison :
a) my Escort 9500ix (and 9500i previously) cannot obtain a satellite signal until my vehicle clears (or exits) my garage, and even then, it's far slower.
b) Garmin Nuvi 360 GPS unit, the GPSMirror still trumps it, by a large margin.
I am also similarly impressed with the speed display and how quickly it refreshes the speed. There seems to be much more "lag" for lack of a better term with the speed display of the both the Escort 9500ix and the Garmin Nuvi 360.
Kudos to the Cheetah designers!
At this point, I would respectfully ask for a way to dim the display on the mirror itself. That would be a useful addition to a fine product.