The original driver didn’t work well on some Snapdragon devices (the LG Expo, for example), and on some ROMs also didn’t work very well, according to some. The new one works on the programs, games, and devices I have tested it on so far, namely OGLCubes, Electopia, GLBenchmark, Manila/TF3D/Sense(/whatever), on a stock (NLD) HTC HD2.
How to test it?
First of all, test if all your apps and games still work. If an app/game does not start at all anymore, go into CF3DConf and set the application’s driver to “Original”. That should let it start again.