Leonard Bernstein was, undoubtedly, one of the big movers and shakers of the 20th century. In his own way as iconic as Elvis, Marilyn and James, he might be called the "great communicator" of the classical world: the popularizer without equal. Part of his success in this came from his own abilities in the popular musical theater genre. Indeed, his best works - by a very long shot - are in this, and similar, veins; one thinks immediately of Candide; West Side Story; Prelude, Fugue and Riffs; On the Town; etc. When he strayed from this stuff, the results ranged from boring through less-than-thrilling to downright embarrassing . Chichester Psalms is one of those pieces that falls through the cracks a bit. It's nowhere near as good as Fancy Free and the like, but it is not as awful as several other works. To paraphrase the old variety show from the early eighties, the first movement "has a good beat; I can dance to it; I give it an 8."
So, enjoy what there is.