I really like the look of the Vr15 a lot better. All the extra bumps and bits on the other one aren't as aesthetically pleasing, and are actually pretty intimidating. I'm not sure if they'd do much more than just the basic design.
We have the VR12 - and we're not terribly impressed with it. The clit vibe is too close coupled to the shaft - so it's hard to get into the right place. We don't have the 15 - I just know it's smaller in diameter.