I've been watching videos of them for over a year but haven't heard one in real life, yet. Has anyone experienced one before? If so what did you think of the quality of music it reproduced?

I doubt there are too many people on here who've heard them. They are pretty rare.

But from the builds, seem fairly easy and not terribly expensive to construct with a little EE knowledge. Too new for reviews?

New ? No, they've been around multiple decades. Just don't see them much.

I guess if you have found a design that is cheap and easy to build, give it a go.