Shostakovich's Symphony No. 4 was suppressed by the composer after the infamous "Muddle instead of Music" article by Stalin, and not performed in public until 1961. There was a very interesting pre-Prom film showing of the Chicago Symphony Orchestra's Beyond the Score presentation about the music. Apparently the first two movements of the symphony had already been written, and only the final movement was written after the article. Shostakovich also considered it to be one of his best works.
I'm not entirely so sure. It's described as his most "Mahlerian" symphony, and whilst I think that is right, it's also the most "Wagnerian" - in the "brilliant moments and tedious half-hours" sense. In the first movement in particular, I find a number of sections which don't seem to have any real purpose. But perhpas ironically, the last movement probably is one of the best and darkest things Shostakovich ever wrote - certainly Bernard Haitink and the CSO had picked a pair of tragic symphonies, with Mahler's sixth the night before.
I don't think Haitink had quite the edge on the previous time I'd seen him, with the BBC SO doing Mahler's Resurrection Symphony in 2006, but his diffident presence on the platform again added so much. I'm reminded of the Great Britons series a few years back, in which the case for Charles Darwin was put that he was not only a great scientist, but also fairly incontrovertibly a nice guy. I think the same could be said of Haitink: it's almost as if his ego has to tolerate his talent, but what a burden to carry.