I wouldn’t recommend it if you don’t have some modular or at least CV-controllable synth gear. I use it in conjunction with my modest eurorack synth setup, and that way I get some pretty cool things out of it. Though I will admit this is usually in the form of samples that I then edit and use in my DAW. Things I’ve used it for so far:
-sequencing the speed of the dc motor to different pitches and then holding it against different contact mic’ed surfaces (for a somewhat more interesting kind-of-sine wave)
-sequencing the dc motor, with a bit of tape stuck on the axis, to strum a guitar string/kalimba/… really fast at some points in my sequence
-scanning through radio frequencies with with an LFO and gating the output rhythmically (for something not unlike the intro to Bloc Party’s “Hunting For Witches”)
-complement my (virtual) drum machines with hits of a real cymbal using the solenoid
-the envelope follower, which is a great addition to any modular system
-feedback drones with the speaker and a contact mic
-making various “boing” sounds by hitting a suspended spring with the solenoid and contact mic’ing the end points of the spring (or just hitting it with your hand or a pen or whatever)
One thing I would suggest if you buy this is to buy a couple rolls of masking tape and some really big paper clamps to hold things in place, and an assortment of springs, as the expansion kit doesn’t really include that many usable springs.