Bob Moog's Etherwave isn't a traditional synthesizer. It's a Theremin. Technically that makes it an even more traditional synth, I guess. It's limited it to pretty much being a one-trick pony. But it's one hell of a trick. A theremin has a classic sound, and very little can adequately duplicate it. And it looks really funky to have someone standing in front of this box waving their arms.
NOT at all easy to play, since its a continuous controller with nothing but aural feedback. But it's a lot of fun.
It's a good buy for its price if you're serious about learning the instrument. Comparative models are either harder to assemble from kits or MUCH more expensive. Plus, since it's a relatively simple kit it's pretty easy to hotwire and modify.
Big Briar plans to make additional retrofits (possibly even MIDI control) in the next year or so.
A very nice little instrument. And if you're into wiring things it's a cheap kit.