This set and the three companion volumes come from the first of Alfred Brendel's three Beethoven cycles. The playing is outstanding - for my money even better than his excellent cycles from the 70s and 90s. Brendel's strength is his ability to create genuine, deeply thought, personal interpretations, without ever going into wilfulness or eccentricity.
The downside? Two things. The recording (analogue, from the 60s), is aceptable rather than great; if digital, crystal clarity is a must this isn't for you. And after listening to this set for a couple of years, I realised that two sonatas, 4 & 20, are missing...!
That said, the playing is the equal of any of the better known, more widely recommended cycles. I love these sonatas, and I've listened to most of the 'great' recordings; but I keep coming back to this set. And when you consider that in amazon marketplace you can buy the four volumes for less than four pounds each, this has to be the ultimate bargain.