This is for tinkerers / hackers. Not for every EFI / engine installer.
Developers mostly use it for experiments (eg. to log v3 data to SD card with timestamps) and CAN-experiments (logging / verifying CAN data to see if it apparently matches certain set of ID-s), although it's capabilities for data processing and interfacing are f'ing awesome. It's a developer's swiss army knife. Requires more patience, reading, soldering to get any use of it than any other device in this shop.
If you're not certain you need it, you do NOT need it.