At this writing there have been two very positive reviews of Haitink's performance of Mahler's Sym. 3.
I will second these recommendations and provide a few of my personal observations to perhaps help explain why I think you will find this such an enjoyable performance:
During the performance, the close-ups are well-planned, and give us a chance to see Mahler's diverse, birdlike chirpings, especially in the first movement and the beginning of the third movement, where the "cuckoo is dead" refrain bounces from oboe to clarinet to piccolo.
Florence Quivar's voice combines a haunting, almost supernatural sound with perfect enunciation--a "John the Baptist"-like voice crying out to mankind.
The final movement is so resolved, so ultimately at peace. Those old enough to remember the ultimate showman, pianist Liberace, will recognize his signature tune, the once popular song, "I'll be Seeing You." An example of pop music with classical roots, the song was taken from the final movement of Mahler's Third.
Liberace started out as an unsuccessful classical musician. He later achieved worldwide fame, wearing extravagant, eye-catching, opulent outfits which complemented his title as "Mr. Showmanship." Yet, remembering his dearly-loved classical music, he always delighted whenever someone in his audiences recognized his themesong as coming from Mahler's Third symphony.
Mahler's Third is certainly a unique piece of music, for Mahler himself said that he was attempting nothing less than to embrace the entire universe in music. This performance does indeed fulfill Mahler's design, beginning with soft sounds, which Bernard Haitink continuously suppresses to even more quietness, until a Liberace-like resplendently triumphant finale.
As Leonardo da Vinci said, "Oh you wretched mortals--open your eyes (and ears!). Really, this is a performance you will enjoy again and again.