I've had my ScanGauge II installed for a couple of months, and I think it's really useful. I missed having the trip computer functions on my CX-7 that I saw on the Ford Edge that we demo'd, especially the "miles to empty" and trip averages displays, and the ScanGauge includes these (and a bunch of other functions).
It took 5 minutes to install, if that. The OBD connector on my vehicle is right next to the steering column, at the leading edge of that under-dash panel, so it was reachable from the driver's seat. I used the included velcro tabs to mount it on the top of the steering wheel lock enclosure, where it's very readable; only the gear indicator light is partially blocked. Was simple to stash the rest of the connector cord behind the dash.
I spent about ten minutes setting it up and reading the manual: displays in English, miles, and gallons; red-orange backlighting to (almost) match the stock gauges coloring; how large is the tank on this vehicle, etc.
The trip functions work great, miles traveled, average mph, and so on. I probably use the mpg functions the most, although I would say it's starting to cause me to exhibit some Prius-like behavior ("just a little lighter throttle and....there...27.1 mpg!!") that my wife thinks is bit too codger-ish. Minor drawback.
I've used the "reset codes" feature once: I got a CEL, and of course figured I had the gas cap issue that's been reported here. I got the code readout, checked it via the internet, and sure enough, was for a "evaporative system / gas cap loose" fault. I checked the gas cap, and indeed it was loose...whether it worked itself off, or I forgot to tighten it I couldn't tell. So I fixed it, and did the "clear codes" function to reset the OBD computer and turn off the CEL. Nice feature to have!
