I do not much like the idea of being the Frank Rich of Mahler 6 recordings, and if someone more qualified has a differing opinion, please feel free to voice it. I am operating without knowledge of the score and consider myself a casual critic at best. I know what I like in a Mahler 6, and I have attempted to set my personal feelings aside and look at it from a more balanced viewpoint.
From the iTunes samples, I was impressed by the acoustics of the new Tennstedt/London Philharmonic Mahler 6 release. I still am impressed by the sound in the hall where this was recorded—where was this taped, by the way?
Upon a closer listening, though, I found many things that I have fault with. First and foremost, the playing is rather sloppy; I do not have access to a copy of the score (I could read it using Braille music, but that would take a while and be very difficult), but I have heard other live Sixths. Generally, in these other live recordings everything as far as the notes are concerned sounds the same. Not with this Tennstedt recording, however. Most noticeably (after a casual listen of at least part of all four movements), the passage leading up to the first hammer blow is lacking the trumpets that--for me, at least--seem to be the dominant force in the melody. The passage sounds empty--to an extent--without said trumpets. Another thing that comes to mind are intonation flaws throughout the work. I will, if people actually wish for such details, go back and listen through for specific examples. Bottom line...there are some things that just don't sound right here.
Another issue unrelated to the performance is how the audio sounds in compressed iTunes Plus format. I can actually notice that the file has been compressed--listen to the opening part of the Andante to see what I mean for the best example)--and that disappoints me given that iTunes Plus format is equivalent to CD quality. I have no idea if it sounds better in straight MP3 format and I have no plans to find out. ;-)