I have been learning this over quite a long time; it really requires constant work to master it. I think it's one of the most difficult solo piano pieces Rachmaninov wrote.
Happily I am nearing mastery of the technical difficulties, the hardest of which I think is the section starting in B major (then modulating considerably) before the main theme returns in the left hand not far from the finish.
By far the most difficult thing about this piece is the interpretation; it's very easy to make it all sound like notes and not be music at all. This however is partly a function of the technical problems.
The best way to overcome the technical issues is to take out a bar or half a bar at a time and play it over 10 or 15 times very slowly. Phrasing is another issue. I found it hard at first to make the melody line 'breathe'.
I think it helps also, to remember the circumstances inthe composer's life surrounding its composition; at the time, he was about to flee the Bolshevik Revolution in 1917, and the whole piece to me reflects Rachmaninov's sadness that the Russia he knew was being engulfed by an alien power, almost. I think this sadness shows in the music. But I see the modulation to E flat major at the end as an indication of hope; that one day he would be able to return. Sadly, that never happened.
