For me the reason to buy this disc is The Vision of St Augustine. This is a truly remarkable work. It is dense and complex and creates it's own vertiginous sound world that is absolutely unforgettable. The work is a tour de force for the solo baritone and John Shirley-Quirk's account is magnificent. Tippett's conducting is committed and authentic (obviously!) but it may be that another, more skilled, conductor would have been able to do more to clarify the textures and a more recent recording might have helped as well. Be all that as it may be - in the fairly unlikely event that a new version were to be recorded in the near future this one would still be an unforgettable classic.
The Rose Lake is a late piece that many find very beautiful. For me, though, it lacks the energy and inventiveness of Tippett's earlier styles (he went through many phases). It is fairly attractive - some nice "African" tuned percussion sounds! - but I find it a little dull. I feel that others have created more compelling sound worlds for achieving the kind of impact that I believe Tippett was after here and that is something I can't imagine saying about many of Tippett's earlier works.