The original WAS great. But, things change.
1. The LCD is small, compared to everything else that is current. And, a larger, hi-res LCD is a good thing.
2. The LCD was useless in bright sunshine.
3. More good pixels is a good thing. You can always shoot with lower resolution, or process RAWs to smaller sizes. There's a 32GB CF card now, for under $300. Hard drives are cheap.
4. "Sturdier" build and "environmental sealing" on the new one. Good. Good.
5. Video. It's a bonus. Don't use it if you don't want to. But, take a look at the sample videos. Shallow DOF. Full 1080p HD. I can see myself making little commercials and snazzy little travel documents and such, if the video can be edited with Final Cut.
6. 14-bit files. Should make gradients and tonality just a weensy bit smoother. And/or help with editing. More info is good.
7. Live view AF for 'stealthy' shooting. Put the mirror up, and it's almost silent.... Silent shutter, AF, 4-frames per second street shooting, with 21MP-worth of cropping potential. Shoot from the hip and re-orient/re-compose it later....