Why was it so popular? Undoubtedly, it was the combination of conductor Bernard Haitink and Gustav Mahler, composer (as Tom Lehrer put it) of "Das Lied Von Der Erde and Other Light Classics". The single work on the programme was his Symphony No 2 (Resurrection). Perhaps it would have been preferable to give Haitink a guest orchestra, such as the Concertgebouw, but he had the BBC Symphony Orchestra, which some people feel is not quite top-notch. Nevertheless, I really think they raised their game; it's often said (and probably true enough) that professional orchestras can play many pieces more-or-less without a conductor, but on this occasion it was clear that Haitink added so much to the performance, a modest but assured presence on the podium.
Unfortunately, I made the mistake of standing with two people both significantly taller than me in my line of sight to the conductor; at 5'11" this does not happen too often, but perhaps I understand obnoxious_muso's problem here a little better now.
The opening Todtenfeier was intense, a study in anguish and grief or a journey to the Underworld. The second and third movements depict remembrances, then the solace of Urlicht leading to the massive finale and choral Aufersteh'n. Perhaps the final movement was a tad slow, but it worked nonetheless. It was certainly an appropriate moment for Sir John Drummond to go. Haitink himself, at 75, looked exhausted, yet the applause seemed to rejuvenate him after a few moments.