The first surprise is the music. Not that it is unexpected for the time period--in fact one might expect the influence of Hummel to be heavy in piano concertos written in the first thirty or so years of the 19th century. No, the surprise is that Ferdinand Ries, whom even his teacher, Beethoven, said sounded too much like him, here doesn't sound very much like old Ludwig. This is especially surprising to me since the only concerto I'd heard by Ries, in a long-gone RCA recording by Felicja Blumenthal (I believe) sounded enough like Beethoven's Third Concerto to be a kissing cousin. Then again, some of the orchestral tutti in the concertos on this Naxos disc--especially in the Opus 123 Concerto (1806)--have a driven, almost demonic quality to them that recalls the older master. But the keyboard writing is clearly influenced by Hummel: it is busy, pearly stuff, with quite a few flashy runs and trills, pretty in its way and undoubtedly quite hard to play. While the writer of the notes to the recording says the Opus 151 (1826) anticipates Chopin, I'd say it simply suggests that early Chopin owes a debt to Hummel too. But whether this concerto looks forward to Chopin or not, it's a very attractive work, well put together and with some fine melodies.
The other surprise is the young, otherwise-unknown-to-me Viennese pianist Christopher Hinterhuber. He plays with the kind of dash and bravura we hear from a Stephen Hough. I certainly will be looking out for more of this young man's recordings. He's ably supported by Uwe Grodd--no surprise there since Grodd has shown himself on other Naxos discs to be an excellent conductor of works from the Classical period. This is a little later than his usual fare, including symphonies of Dittersdorf and Vanhal, though he does have a superb recording of Hummel choral works to his credit; I highly recommend that as well.
The New Zealand Symphony is a very competent body of musicians apparently and play with a robust tone in the more Beethovenian bits. The recording places them a little too much in the background, or maybe it captures Hinterhuber with such powerful, front-and-center clarity that the orchestra only seems a bit distant. In any event, it's a decent recording overall.
If you know and like Ries's symphonies or the piano concertos of Hummel, I think you'll be pleasantly surprised as well by this disc.