Santana necks are some of the most hand-filling from PRS, definitely deeper and fuller than the pattern regular or older 'standard'. FTR, I still have a Santana Brazilian Ltd. (full Brazzy neck), and have owned two older Santana sigs as well as an S-III. All had big necks but were slightly different.
As for sounds, I find the breed to sound consistently thick and full, kinda like a good LP in some ways, but also surprisingly rich with the knobs rolled off a bit for smooth jazz type tones. And as others mentioned, unlike many other PRS models with wide ranging switching options, Santanas are fairly simple but still remarkably versatile. Mine sounds so good it scares my LPs.