I've listened to a fair amount of Martinu's music and enjoyed much of it. I wasn't familiar with most of the piano concertos so was tempted into purchasing the Naxos series. The first volume with the Third and Fifth concertos was quite impressive - particularly the fifth. The piano part was very clear and though the Martinu orchestra was less than refined it didn't diminish the piece.
I happily snapped up this volume. Having been unfamiliar with it I found the Fourth Concerto to be a revelation. The two movements sound improvisatory with a very flexible dreamlike lyricism not unlike the sixth symphony. Even so, I've never heard another concerto quite like it. Place that next to his other master concerto, his Double Concerto and the contrast couldn't be greater - two completely different pieces written by the same man and both obvious masterpieces. The fourth anticipates the sound world of Lutoslawski whilst retaining tonality - though it still sounds more radical than the later works of Lutoslawski himself.
So why only four stars? Giorgio Koukl is a Martinu specialist but his style is quite reserved and classical, not in keeping with the nature of this piece. He fairs much better in the spiky neo baroque music of the first concerto and the slightly more expansive second.
There are other reasons too; the first concerto seems to go on for too long - its finale sounds like it is chattering away to itself endlessly and your interest drifts - that's the composer's fault though. The second fairs a little better but though the Orchestra may take the composer's name they're hardly the last word in producing the definitive Martinu sound. They are a pretty average ensemble compared, say, to the Czech Philharmonic, and not helped by a very unsympathetic sound recording. It is a great shame that they really seem to struggle in the subtleties of the Fourth concerto. Yet, even then you can tell that this is great music. There must be better recordings to be had elsewhere though.
This may be cheap but my advice is shop around for the Fourth Concerto, think how great it could sound in the right hands. Even so, this recording is still decent for the price and if alternative recordings of the Fourth are hard to come by then I can still warmly recommend this.