It seems pretty flat to me, personally (the playing..) but it could just be the composition, which is far from Rachmaninoff's finest lol. And, the "not-quite-so-stellar" sound quality could have something to do with it, I suppose. In the end, he'd probably sound more capable playing a better composition, like one the Chopin nocturnes you listed.
One should either be a work of art, or wear a work of art.
You know, some people just have natural talents-like some people play the piano but aren't very tall.