How I Learned to Stop Worrying and Love Slow Beethoven
There are certain pieces of Beethoven's, particularly in his 'late' period, that are so static that they do not have any of the properties we generally associate with great music. There is no rhythmic variety, no contrast or variation, only a static sense of contemplation to which you can either surrender or resist.
Even at Beethoven's prescribed (surprisingly fast) tempo of 60 beats per-minute, there are far from enough 'signposts' that your attention will be held in the manner of a Mozart piano concerto or even a Middle-Period Beethoven Symphony. You're thrown into the music, immersed in a warm bath of pleasing sonorities without any genuine sense of the direction the music is heading.
Beethoven's need to challenge the listener can occasionally be as troubling as it is invigorating. But there are very few musicians (or artists in general) who have enough variety in their work for all moods. When played compellingly, there may be no composer whose work has more of that variety. And he will continue to engage and confound his listeners for as long as music still exists.