Summary: It's simple, without any ado and meets my expectations perfectly. There are keyboards that has more functions, and I already had one of those before I bought this - the KeyRig was worth buying just because it's so simple. And no software! Logic Pro and Ableton Live instantly recognizes it, and I can start making music right away.
Summary: I got this keyboard late last year and have been very impressed with it. I'm currently using it as a midi controller for garageband on my mac and it works great it responds well and is pressure sensitive so the harder you play a note the louder it is. overall this keyboard has served me well pared with the M-Audio SP-2 US65010 Sustain Pedal Piano Style Sustain Pedal for Keyboards makes it perfect.
Summary: The M-Audio KeyRig 49 is a great tool for the musician looking to add a midi controller through the usb port. I am using a 3 year old MacBook Pro and have done lots of recording of guitars and vocals in Logic. This year I decided this old dog should learn a few new tricks, so I picked up the KeyRig 49 and plugged it in. If you have GarageBand or any of the Logic products, this is a great learning tool.
Summary: I purchased this keyboard for use with Finale 2010 on my Mac. It works as I expected and I have had no problems so far. As others have noted, the keys are not weighted, but for note entry it works as I would like. I also like that it is a half size keyboard so it is easy to store. I didn't need any extra functions and this keyboard is simple. I only use it for note entry.
Summary: All you have to do is plug it in to your computer's USB port, turn it on, and run SimplePiano, or any other similar free Windows program that takes input from a MIDI device and outputs it to the MIDI sound output that comes with Windows, and start playing. It's perfect on my lap, with my laptop computer on the table. You can play 4 octaves on it without having to use the octave-shift buttons.
Summary: This keyboard is perfect for basic MIDI entry, which is all I need - it's compact, light, portable, and USB powered. The only problem is, there is no gig bag that I can find that fits a keyboard like this. All gig bags are 14 to 15 inches deep and 5 inches high, while the keyboard is only 8 inches deep and 3 inches high. The box that it came in has a plastic handle, but who wants to use a cardboard box as the carrying case?
Summary: Though it does have a bit of a toy-ish feel, this serves my needs perfectly. If you are someone who is looking to perfect their piano playing, I don't highly recommend it, because it is not the greatest reproduction of a real piano. However, if you are someone like me with not a lot of money but needs the ability to control a wide range of sounds, it definitely does the trick.