I haven't got the motion+ yet, anyway the original wiimote uses X, Y and Z values for the position of the remote. If you get an accumulator demo (wii homebrew) for the wiimote you can see the values of each when you hold the wiimote in different positions or swing it. What you notice is that X and Y values follows tilting of the wiimote to the sides, forward and backward quite precisely, while the Z-value doesn't seem to be much of use. Though, what I'm not so sure of, is if the motion+ simply improves precision to these values (Which would mean especially the Z), or if it adds any more values. It does seems possible that it could improve some non-motion+ game, unless perhaps the whole accessory is completely disabled for those games.
Specs: intel i5 3570k @ 3.4GHz;
16Gb RAM; Raedon HD 7900;
Win8 64-Bit
16Gb RAM; Raedon HD 7900;
Win8 64-Bit
