I know that some people don't like the tempi, thinks that the orchestra is below par etc. But honestly - I can't hear that.
Of course I hear slower tempi than many "modern" recording, but it's tempi making perfect sense. (Also remember that Klemperer actually assisted Mahler when Mahler conducted this symphony.) Maybe some moderna conductors are just not able to let a slower tempo live?
This is a recording where every note has a consequence in what follows. The symphony is played as a whole, not separated parts that should be as "beautiful" as possible.
The soloists and the chorus are at their very best. There is attack, dynamics, clarity.
This is my definitive recording of this sublime music.