I have volumes 2-4 (all three disc sets, I do not have the single disc volume 1 of the op.31 sonatas). These are straightforward performances with less drama than most. Leaving aside the British critics (who have hailed his Schubert and Liszt recordings from a couple of years ago as also great; and truth to tell his Schubert D958 & 959 are not bad) there were enough who were indifferent or had negative reactions, mostly because of such castration. Though they are played competently, you will hear less extreme tempos and less of a dynamic range here than in most other recordings of the sonatas. Quite good sound, recorded clearly but not too closely. His proponents have said that he is truer to the score than those "more dramatic" readings. Whether that it true or not if you already have number of recordings of these sonatas this is not a set I would recommend in that I do not think it provides a fresh/interesting perspective (whereas for a first set it might be alright, good sound, can be had relatively cheaply, and the mostly middle-of-the-road performances will not bother those with a passing familiarity of the music). Though I have not done a side-by-side comparison, of the recent cycles, I prefer to listen to Schiff's or Brautigam's (on fortepiano, of course).
Thanks Gökhan. A respected Dutch critic was also quite enthusiastic about Lewis' performances, that's what made me curious. I think I'll pass, though, I don't need "middle-of-the-road" interpretations.
Speaking of (and with ) the Dutch, has anyone else been keeping up with Ronald Brautigam's ongoing hybrid-SACD fortepiano Beethoven sonata cycle on BIS? I have all 6 discs issued so far (looks like 2 more discs will complete the sonata cycle), and have thoroughly enjoyed them.