There is nothing special about Karajan's 9th...except the last movement has its good points.
But you've obviously not heard other recordings if you think that Karajan is great here.
Being a Karajan "fanboy" as I assuredly am, I will nonetheless have to agree. Karajan only got the grip of the "New World" the very last time he recorded it (on video); and by that time, he was too old to truly "work his magic" on the piece, in my opinion.
I mean, just listen to Kubelík's recording with (Karajan's) Berlin Philharmonic, and you (or at least I) immediately feel so much closer to the "heart" of the music - or the heart of the idiom, if you want to be more academic about it...