I just picked it up over the weekend, so I've only had a few hours with it but so far it seems quite neat. I'm using it with Windows 7 and Pro Tools 9 over a wifi router (as opposed to ad-hoc) on an ipad 3. The mixer section has very little lag (after turning off bluetooth on the ipad) and having multi-touch on the faders is quite nice since I don't have a dedicated controller.
The "window" system is where things get really interesting. It allows you to see and operate any open window on your computer (that you can control with the mouse), plus your desktop, which also allows you to actually open windows and programs away from your computer. One benefit for me is that I can use it to control my speaker/headphone mix and gain levels on the ipad via my RME mixer while I'm away from the computer recording myself. And, as advertised, it does indeed allow you to adjust plugin settings, etc with touch-- anything that uses mouse clicks or click-and-drag as I don't think there's a way to input text (but please correct me if I'm wrong!).
In the limited time I've had with it, I'm quite impressed. Since you could use this to control just about everything, the next step for me is waiting for the "sheen" to wear off a bit and figure out what I should be using it for and what's faster with a mouse and keyboard.
BTW, if you have any specific questions, let me know and I'll see if I can figure it out.