Yes, we have been testing one and love it. Actually we have the Scan Gauge II.
There are twelve different gauges, and you can display any four of them at any time: fuel economy, fuel pressure, battery voltage, coolant temperature, intake air temperature, engine speed (rpm), vehicle speed (mph), manifold pressure (not available on some vehicles), engine load, throttle position, ignition timing and open/closed loop.
The scan tool reads trouble codes, reads conditions that set the trouble code, clears trouble codes, turns off the "check engine" light, tells you when vehicle is ready to pass OBD-II smog testing and makes and stores up to ten rewritable special codes to send to the vehicle computer.
The trip computer allows you to store eleven different parameters: maximum speed, average speed, maximum coolant temperature, maximum RPM, driving time, driving distance, fuel used, trip fuel economy, distance to empty, time to empty, fuel to empty.
While using the ScanGauge II I have loved the MPG info. We all guess about our mileage. But that's nothing like watching it change as you drive down the road. Being able to find the just the right balance of speed and MPG during a long trip was really nice. When you pull into the gas station and fill up, you tell the computer how much gas you put in. It will make a guess, but you can adjust it to the actual amount added to the tank. With this info over a period of time, the gauge can adjust to give more accurate readings.
Prior to buying the ScanGauge II, I was going to add a gauge pod, but now I don't need to. To top it all off, the ScanGauge II was cheaper.