The best way I can find to describe this recording is a good effort that doesn't quite succeed as it should, and much of the problem lies with the conducting.
But first to some positives. The recording features two very earnest and solid singing efforts. Margaret Jane Wray's accounts of Isolde and Brunnhilde are on the whole recommendable. On the whole her work is lovely.
What's intersting is that hers is a lyrical voice, perhaps more at home in Verdi or Strauss than in Wagner. I would love to hear her tackle either of Verdi's Amelias, or Abigaille, or even Aida. Ditto that for Strauss's Arabella or Ariadne.
All of that said, the freshness and comparative lightness of the voice makes her characters rather youthful which is a nice change from the more stentorian Wagner you may be used to. Her musicianship is solid. She is obviously quite accomplished.
John Horton Murray makes for an ardent and earnest Tristan, his entrance into Act II sounds almost as if he were bursting into a Puccini. As with Ms. Wray, that Italianate warmth was refreshing. His somewhat reedy tenor may not be suited to the rigors of Tristan in the opera house, but on disc it's not a problem. I applaud the energy and drive he finds in the character.
Nancy Maultsby is perfectly serviceable as Brangane though not particularly memorable (and to be fair, it's not a glamor role).
Where the recording runs into trouble is with the conducting. John McGlinn struggles to find just the right feel for two of Wagner's signature scores, and he never really finds it. He fares much better in "Tristan and Isolde" where the orchestra is supporting the singers. However, in "Gotterdamerung" with its exposed orchestral passages, the effect is leaden and sluggish. There is an inexplicable tendency to play Wagner's rapturous music with a respectful detachment.
Because of this, the Russian State Symphony Orchestra sounds anemic and underpowered. This lack of thunder undermines the singers, particularly Ms Wray as she makes her way admirably through the Immolation Scene with a strong sense of pitch and a steady, clean vibrato. A more energetic reading of the score may have given Ms. Wray more to work with. In spots she too seems a little underpowered.
I'd recommend these recordings as a second or third choice. They are not terrible by any means, but they are also somewhat disappointing. That said, the singers are commendable and deserve to be heard in better circumstances. I recommend this recording for their efforts.