4 of my guitars have scalloped freboards. It really makes them a lot easier to play, and combined with a low action, makes them far superior to regular necks (in my opinion at least). The problem with it is that so many people, even after using them for a while, aren't able (or don't realize they need to) to develop the light touch that a scalloped fretboard requires. If you look at Yngwie or Joe Stump playing, you can hardly even tell that their fingers are moving sometimes. Even when you're playing rhythm, or doing vibrato on a string, you have to have the lightest touch possible. Some people would swear I'm not even touching the strings sometimes when I play.

As for rhythm playing, its weird at first, especially if you play a real fast or heavy rhythm style..but you get used to it.

My favorite thing about it is all the cool vibrato I can do though. I can tap the higher frets with my right hand, and vibrato those, bend them around, even fret the strings much easier.