This is no doubt the finest performance from Berstein's earlier stereo recordings of Mahler cycle, Sony. First, I was surprised by the lack of "Bernstein-Neuroticism", especailly in the 1st movement which takes 10 minutes or so to warm up and is a bit too polite for Bernstein. But probably that's exactly the reason why this recording was recommended as a first choice in BBC Radio 3 Building a Library, alongside Chailly's Decca recording (very uninspired, clinical performance to me). I would prefer Berstein's explosive approach, like his live recording of 9th with BPO, but this recording of 3rd is still very strong and eloquent.
What is most outstanding about this performance is the deeply prayerful account of the last movement. It opens in dangerously slow tempo, yet Bernstein masterfully manages to sustain flexible tempi of the ebb and flow of the music, and buils up emotional force in most powerful way towards each climax. Final apotheosis is simply glorious!
Don't worry about recording quality. It's surprisingly good and spacious for 60s' stereo standard.