If you do have the software in the background you get:
Additional force feedback events
Recording of laps for their lap analyzer
I find that I prefer just the builtin/storable settings when driving. You can use the software to change basic settings in the wheel and then store them to the wheel.
The full-feature software, quite frankly, isn't that great. On the other hand the wheel works just fine even without ever using their software, which was a major advantage for me (when I spend $1000 I don't want software involved that might become unavailable).