First of all the subtitler, (a person or group by the name of safetydance) did an amazing job. Damn good for a fansub. The rips are in HD, and look amazing. This animation is 20 years old, yet it looks brand new.
For the voice acting, the living voice actors re-recorded their lines, however, for deceased voice actors, they found actors that sound quite similar, like for Muten-Roshi. You can tell it's different, but not by much.
Sound effects are re-recorded and in stereo, they sound top notch. The new music is different, but still fitting, much better than the horrible U.S. track that was added. I'll be interested to see if they keep vocal tracks in key scenes (Gohan's exploding anger against Cell comes to mind).
The increased pacing is definitely evident, thing are already speeding along. The editing is done well, I'd eventually like to sit down and do a side-by-side comparison to see exactly what was removed.
Another really nice thing that they do is introduce flashbacks, as Dragon Ball Kai doesn't assume you've seen the original Dragon Ball, as Dragon Ball Z did. For instance, the first episode begins with a flashback of Goku's father Bardock battling Freeza. This is footage taken from the Dragon Ball Z TV Special. The beginning of the second episode has Goku sensing Piccolo has returned, and shows footage taken from the original Dragon Ball of their final battle. Again, a nice flashback to establish the background of the characters and set the scene.
Overall, I'm really happy with this refresh of the series, it makes me excited to watch it all over again. I'll look forward to firing up the PS3 and watching them each week for the next couple years... It's also a great way to introduce yourself to the series if you've never seen it (hint: Koop and Kevin).
Here's the refreshed opening song for Dragon Ball Kai: