sam, im afraid to say, i must partially disagree with you....
if one wanted to be really harsh about it, pretty much the WHOLE SONATA "does nothing"... it's all filler, and a crap piece... especially when you compare it to his symphonies [2+3].
so then, this piece really comes down to what the pianist does WITH it, which could be alot [if you are rach or horowitz], or nothing at all, or somewhere in between.
in any case, assuming you met mr rachmaninov, say in Steinway Basement in 1914, and he showed you his Second Sonata... would you really tell him you thought his piece had "filler" in it? i'd probably tell him his piece was wonderful, and could i have a job cleaning his house?

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