Of all of Karajan's recordings of Mahler's symphonies, the ones that have received the highest praise have been his two accounts of the Ninth, and some feel the latter live performance of these is the better. I have not heard that recording, but can recommend the first one offered here. In comparison to his 5th, this account of the 9th is perhaps a bit more controlled and emotionally restrained, and Karajan's reading does not allow Mahler to, so to speak, wear his heart on his sleeve. It is close in tempo and interpretation to Haitink's famous record with the Concertgebouw, and has a slightly brisker tempo than Klemperer with the Philharmonia. It is not as aggressive or forward in sound as the Solti 9th, although a case could be made that Solti's approach comes closer to the letter of the score. In comparison to Barbirolli's wonderful performance with the BPO, the Karajan has better sound but not better playing - maybe not even as good in the woodwind in fact. The strings in both performance are very beautiful, and the superior sound gives the Karajan an advantage here. The inner movements could be a bit more incisive in rythmic pointing, but they still work well. The outer movements are slow but not excessively so.
Christa Ludwig's performances of the Kindertotenlieder and 5 Ruckert Lieder, previously coupled with Karajan's reading of Mahler's 6th Symphony, remain outstanding, and she receives excellent support from the orchestra.
The documentation is excellent too and at medium price this can be recommended. I still like the Solti 9th best of all (although the interpretation has not received unaminous praise), because the CSO's playing is in a class of its own, and is superbly recorded.