I'm afraid I must concur with the lukewarm overall rating this item received until now. The playing is fine, the singing excellent, yet things do not come together in a way that reaches the core of this magnificent, dark piece. It's all just too polished and comfortable for that, much like the Ozawa Boston version, though this one at least has more energy and variety than that monochrome reading. Also, the singing of Frank Lopardo is not nearly as awful as that of some of his colleagues on other issues.
A common misconception plaguing this piece (and repeated in a review below) is that the Berlioz Requiem is all about producing lots of noise. But most of this work is quiet, inward-looking and remarkably spare (including a Quaerens Me for unaccompanied chorus) . Rarely, in the many contemplative passages, does one feel that Spano and his team are truly in touch with the message, and the one-disc format alone seems proof that contemplation is not their forte. The earlier Shaw with the same forces is much to be preferred.
Soundwise too this disc offers a strangely mixed experience. Clearly intended as a sonic spectacular, it doesn't really deliver the goods. The Dies Irae is efficient rather than overwhelming, though the spatial layout is effectively conferred even in normal stereo. But the drums lack power and definition, and there is no sense of menace when the entry of the fourth brass group uproots the triumphant fanfares by introducing a seventh chord. Also, I was bothered by a faint but persistent electrical background hum which became rather annoying when listening through headphones.
On the plus side, the recording is very detailed, and therefore useful for study purposes. But most of us will want this music for other than academic ends. If so, moving and memorable alternatives are available from Norrington (Hännsler), De Billy (Oehms - but forget the Sanctus), or Dutoit (Decca). Davis too is generally recommended, though personally I do not share the high regard in which it seems to be held. Unfortunately for all lovers of this greatest of all Requiems, the definitive recording of it (if such a thing exists at all...) has yet to be made. Maybe a dedicated period performance under Gardiner might do the trick...?