Factory Sealed an out of print!
Beethoven's piano sonatas were one of humanity's great achievements. They have been recorded by many pianists including Artur Schnabel, Alfred Brendel, Richard Goode, and John O'Connor--and nearly every pianist of note has recorded at least a few of the most popular sonatas.
What makes the Kempff set work best for me is the lack of a dogmatic, cookie cutter approach to the music. Kempff approaches each piece as a masterwork in its' own right. The tempos are more sensible than those adopted by most other pianists, particularly in the slower movements. For example, in the Hammerklavier Sonata, most pianists cannot resist the urge to play the Adagio almost as a Largo--ignoring the fact that such a tempo would have made the movement incomprehensible on a piano of Beethoven's time--which had a quick tonal decay. Speaking of tone, Kempff has an especially beautiful sound--a product of his 19th century training. The phrasing is more flexible than today's "red light, green light" stop and go approach, and Kempff, unlike so many of today's pianists, never lets musical point making get in the way of the big picture, structually.
Although Kempff was getting along in years when these recordings were made--the 1960s--he is fully up to the technical hurdles these sonatas contain.