You can look up alll the changes between the two, basically more HP/TRQ, improved trans, rear end, and clutch, tires maybe a few more?
As for driving; clutch is different, lighter and engages differently, some people stall it when they first drive it.
Shifter linkage travel is reduced, (much closer to what a B&M kit feels like), I swapped to a shorter shifter and this is the first viper I've owned that I didn't change out the shift linkage.
Drive by wire, you'll feel a delay in the throttle engagement vs. other Gen's. I added the mopar ecu but there is still some lag compared to older Gen's
Tires, the non-run flat PS-2's ride and handle better (hopefully you upgraded your run-flats so you know what the difference feels like).
Motor, the Gen IV's make more power but later in the rpm band, you feel the cam-in-cam coming on around 3500 RPM, vs. older Gen's that have a flatter more linear power band.
I'm real happy about the Gen IV, would think the only people that would have a regret would be due to either, the cost differentail or the fact that you can't add a supercharger or twin turbo. Good luck, Mike