The weakness is the lack, sometimes, a certain abandon that deprives the most heroic Sonatas (Waldstein, Appassionata) of their volcanic fury. The interpretation of these sonatas is beautifully mastered, but it lacks a bit of vitality.
The magnificent qualities, in particular the absolute success of the last three sonatas and Hammerklavier: here Brendel find the ideal balance between control and freedom, and he takes us on summits. There is also the extraordinary work done on certain sonatas, like the sonatas No. 16 and 18 whose internal movement has never been well articulated.
The magnificent qualities, it's also the sound that are taken from end to end, exceptional warmth and presence.
So even though I also own integrals Nat, Backhaus, Brendel (1st version) and Arrau (2nd version), it is probably all the more homogeneous and contains only successes I would not pass me.