I must have heard all of Beethoven's piano sonatas (and yet have not found no match for Gulda's interpretation) at least 100 times, and I can say that it's all there. All of the sentiment in music, the power, the joy, the laugh, the suffering, the pause, the voices... it's all there. I think that if an alien came to earth and asked me: "show me what have you people created in terms of music", I would present Beethoven's piano sonatas. "Mr Alien, there are a lot of other good things, very fine things, but if you take this home you will be satisfied. All of our music is here, the rest is lesser."
(I strongly recommend you to get all of his piano sonatas, easily found on the internet. And take my word, there is no match for Gulda, don't even bother getting another one.)