Starting with the reason why this is a vital purchase for any Renee Fleming fan (or even any fan of a great singer / actor)--it may be the best thing she has ever done. She uses every dynamic, every color, every movement, every reaction to her fellow singers you can imagine to create a one-of-a-kind "living" woman, and a few ideas you probably won't expect. (The last minute of Act One is infinitely touching without a note sung...just to name one.) If you are a fan of hers, you will find nothing to complain about and so much to admire--the tricky mixture of sadness, irritation, pain, love, and even a touch of humor that makes up the final meeting of Octavian in Act One. She does not "milk" the monologue about the clocks, which makes it all the more touching. Her final appearance in the opera, including the heartbreak of the Trio, is a marvel to watch and hear. In its subtlety and range and originality, her Marschallin is unmatched. Really, this is a truly great operatic portrayal, to rank and even surpass the wonderful Schwarzhopf in the famous filmed version. (She certainly seems more "girlish"--Octavian would not fall in love with a "mature" woman. He sees no difference between them, age or otherwise. Important and usually ignored, especially by a few too many people who swear they know Rosenkavalier backward and forward. Why do so many of them think the Marschallin is a middle-aged woman?) The comic roles (certainly "buffo" and played broadly) mostly work very well and though Hawlata is far from the greatest "singer" of Ochs, he is lovably obnoxious and even rather pathetic when confronted with his own foolishness. He seems within the character word for word and it shows. His vocal shortcomings are not so grave as to keep you from enjoying him. And Jonas Kaufmann is quite funny as a tenor who brings in paparazzi as well as an agent! The conducting by Thielemann is free from the "squareness" that sometimes mars his conducting. He is flexible and free and follows the singers like a glove. When a firmer hand is needed, it is there. In fact, his control over line, shape, and dynamics to match Fleming is one of the best selling points of the recording. The production is beautiful to look at, the updating unobtrusive (how often is that the case?) and the directing makes all the elements work as a frame for characters not just singers, especially the use of mirrors as a meaningful and unifying device. A few comic pieces of business don't quite work but they are few and short and far between. Costumes, lighting, etc. are all of a piece. This should be a given at all times in every production, but so rarely is. No, it is not Zeffirelli realism, but all the better for it as far as I am concerned. (You know if you are not in agreement, so take that into consideration.) And the "problem" of the young black servant which is a little too redolent of its time period--and not ours--is cleverly "solved."
Now the disappointments. And they are grave (to me...some people might not be as bothered, but I have to say what I feel.) Neither Sophie Koch or Diana Damrau, though musical, and intelligent and characterful, sing beautifully in the highest registers--and their roles lie high much of the time. Beautiful passages will be marred over and over by strain and shrillness. Koch is more forgivable in Act One because she is supposed to be highly strung, but even then strain distracts. Sadly, the next two acts get worse and worse. Damrau is just as bad. She has some undeniably lovely moments but she has more strained ones, culminating with her entrance in the Trio that has to be the ugliest version I have ever heard. This is not world-class singing, no matter how many people claim it is. I wish it were different. She is musical and she can act. But the singing is too often unpleasant. She is straining, forcing the tone, no two ways about it. And Koch's part in the Trio is not much better. So the opera's highlight is only a highlight in Fleming's singing and acting. A major mark against it. Luckily, the orchestra supports the rise at the end of the Trio before the key change with such a full set of strings, the harshness of the two "outer" voices have their shrillness tempered some, so at least the payoff is still effective. Disappointing, though. VERY disappointing.
Hard to give a star rating but four stars for what is (truly) great that will hopefully help you overcome the vocal shortcomings.
NOTE: I watched it two more times. I liked Koch better than I did. The last two acts lie lower, so her singing (sans Trio) is less harsh than Act One. Still feel the same about Damrau, alas, though the final duets are lovely.