Lacking development, rather "ordinary" when comparing with the composer's more "powerful" pieces.
Imbalance among the solo instruments, the piano part is simpler, though supposedly intended by the composer since the piece was dedicated to a client who was very supportive of the composer and who was a less skilled pianist.
Etc.
But many still think it is as great a piece and believe it is underrated. One interesting comment states that it can be considered as Beethoven's concerto for the cello.
I myself am a simpler listener. The cello speaks thoroughly a clear, clean, authentic, deep and fresh enough inspiration, this is good enough for me. I can't tell the rest anyways.
