my friend actually bought it yesterday and we were playing around with it. as with any accelerometer, it needs to maintain its orientation in whatever setting it is used in once calibrated, or else the information will be quite off...
by simply tilting it backwards during your 1/4 mile run, we were able to get sub-10 second 1/4mile times. add in a spin while it's recording, and we were able to get passes in the 6s range at 288 mph!...
but that's besides the point. it measures distance traveled by your rate of acceleration, and seems to be pretty good. (we tried a running with it) anyway, a fun little toy for the price, and probably just as good as similar products like the entry level g-tech.
we're doing some vehicle testing using accelerometers and other data acquisition systems so we're gonna put our National Instruments setup ($$$) next to this program to compare the results. should be fun to see.