The M-Audio Axiom 25 is a 25 semi-weighted key MIDI controller. It notably has eight trigger pads for controlling drum samples, and eight knobs for controlling effects and oscillators on virtual synthesizer instruments and effects. It also has the usual transpose, octave, pitch-wheel, and modulation wheel features. The 25-keyed model lacks the fader sliders that the more-keyed models have.
I bought the Axiom after owning an older Edirol MIDI controller which had 61 keys, and as I was producing pop music now I didn't need as many keys to perform what I needed. I must say I'm impressed by the unit's durability and solid contruction. One thing that sets the Axiom apart from the other types of keyboards out there right now is it's semi-weighted keys which gives the unit a more "piano-playing" feel. Most keyboards and controllers at this price have hollow keys which often feel cheap and the desired action isn't achieved when playing.
Overall, I'd say I' pleased with the Axiom, as little as I use it. It has enough features and it's built solidly for adding organ and keyboard parts to pop and rock guitar-dominated music.