Included on the keyboard is a small clickpoint/joystick, two rotary knobs (assignable), and an array of fully-assignable wheels, knobs, and dials.
PerformanceI bought the K25 as an affordable way to use keyboard plug-ins, including B4 and Abbey Road Keys. A client needed to use it, and I didn't have one on hand. For $99, it was an easy investment.
A quick warning to my fellow Mac users: plugging in the K25 to my USB port on my Mac, I was very surprised -- my trackpad quit working! Turns out, the (very slow-response and fairly useless) clickpoint on the K25 automatically became my default mouse; after poking around in the Mac's system settings, I was able to ignore the USB mouse easily, but it still gave me quite a bit of frustration.
Getting the K25 to work with my Pro Tools system wasn't a huge ordeal, but it continuously threw out HUI errors which required some minor troubleshooting.
The controller worked fine -- 90% of the time. The other 10%, it would start sending mixed signals to the host program, and caused some really interesting-sounding arrangements to come out of my otherwise solid organ lines. And trying the K25 with other host programs, the same problem happened. Overall, I decided it wasn't for me -- and waited in line for an hour at Guitar Center to return it.
For home recording using Garageband, I'm sure it'd be fine; in fact, the K25 comes with some great demo software to get you started. But in my professional, profit-earning Pro Tools-based studio, it simply didn't deliver every time I needed it. Remember, downtime equals profits being lost. For $99, it's certainly affordable for those who need something quick and cheap -- just don't rely on it when you won't have a chance to do the take again.