I've been using the white xplorer GHIII model, but after hearing a friend rave about the Rock Band 2 Wireless one, I ordered it.
I'll see how much I dig it when it arrives tomorrow.
Ok, I just got it, and started playing immediately, Wow, huge difference from that white xplorer model I've been using. This thing rocks, it doesn't feel cheap in my hands at all. The buttons are so much better and the strum bar is fantastic.
But, I must say, the best part of it is how sensative the tilt sensor is for overdrive. no more jerking the hell out of the thing and ending up screwing the song up, just a slight tilt and bam!
Overall opinion? Awesome!