The piece in question, one of the great thorny challenges of the piano repertoire, is the Sonata in B flat, op 106 by Beethoven. Here is the original title page:
Now "Hammer-Klavier" in German just means "keyboard with hammers" as opposed to the older harpsichord which is a keyboard with plectra. Beethoven went through a nationalist phase where he began to use German tempo words instead of Italian ones. "Pianoforte" is, of course, an Italian word that points to the ability of the keyboard with hammers instead of plectra to play both soft and loud. In any case, the word "Hammer-Klavier" does not signify that this piece is particularly loud or fierce. It is just a handy nickname like "Moonlight" Sonata or "The Tempest".
In order that the comparisons be fair, you should listen to these clips with the score and NOT watching the videos.
This is quite a long sonata, between forty and fifty minutes depending, so I will just talk about the first movement. I have listened to two performances of the the first movement by each performer. Let's listen first to Yuja Wang at the Verbier Festival this year:
The first movement is about nine minutes long in this performance. Next is the performance at Carnegie Hall this year and the first movement is a little over eleven minutes long:
Then we have Grigory Sokolov in a performance at Munich in 1975. He also takes around eleven minutes for the first movement:
The final one I listened to is on this CD: Sokolov: Schubert/Beethoven and it is the longest of all; the first movement takes almost fourteen minutes. For some inexplicable reason, Blogger won't embed the clip, so just follow the link:
Trust me, it is worth it. This last clip, recorded in a concert in Salzburg in 2013, was just put up on Aug. 23 and so far has had only five views! It has been released on this CD, which I recommend (for the Schubert even more than the Beethoven):
What I would like to do at this point is nothing. I have taken away Yuja Wang's huge publicity advantage and just posted two of her performances followed by two of Grigory Sokolov's and all you have to do is listen to them. Preferably watching the score, not the video! Then you can simply come to your own conclusions! But I am happy to offer a couple of thoughts. It is actually very hard to put one's reactions into words. Often one musician will run into another coming out of a concert and one will simply shake their head while the other returns that with a smile. Yes, we both know what we think and no need to put it into words.
It is hard to put into words because, while I think it is quite clear who is the better performer of this sonata, exactly why is not so accessible in language. For example, while what Yuja Wang does is certainly very accomplished and quite correct: notes in the right places, dynamics tidily done, phrases phrased and so on, it never seems to amount to much. Whereas, Sokolov, even in the early performance which is full of fire and rhythm, always seems to be revealing something: inner voices, that bass line you never noticed, the whole of that odd harmony. And he is always with where the harmony is going. The last performance, the slowest of all, is also the finest. Things that don't make a lot of sense when they are rushed become clear and inevitable at the slower tempo. And yes, there is some controversy about Beethoven's tempo markings.
But really, were you expecting anything else? Really? As a very seasoned Czech violinist said to me as we ran into one another leaving a concert by a young Canadian cellist, "what, you were expecting Rostropovich, maybe?"