THinking about getting one for one of my cars with an OBD port. It looks like the set price is $159, and also the lowest I've seen new.

Is this gadget worth the money, and how accurate is it? I'm interested in getting temperature readings, among other info the SG gives.

Is this a plug and play device? Or is there some setup and prgramming involved? It would be nice to switch to other cars or if a friend needs some codes read.