The music sounds quite off-the-wall, with the majority of it sounding like improvisation. But it's generally not too hard to swallow; I think because they're playing clearly, and they seem to balance each other nicely and keep it all on track. It never sounds too grating or harsh either, because their playing is lively without being over-the-top.
There are some lively rythyms which sound like they come from traditional American dances, and some 'jazzy' sounds too. Also some quite exciting flourishes and interplay between the violin and piano.
The first three sonatas tend to meander around quite a bit, and it's difficult to tell where one sonata ends and the next begins. The fourth sonata is the most concise and cohesive. It has a catchy rythym in the first movement, and in the second movement, a beautiful wistful melody emerging from a wandering violin line. A playful tune in the last movement gives way to a rather abrupt end to the sonata.
If you like your music with a strict time that you can follow and clearly defined melodies, don't buy it; it'll do your head in. But if you're not too demanding that way, and you want about an hour's worth of music with an edgy, improvisational feel and some catchy bits, give it a go!