Geri Allen is the quintessence of what a late-'90s mainstream jazz musician should be. Well versed in a variety of modern jazz styles, from bop to free, Allen steers a middle course in her own music, speaking in a cultivated and moderately distinctive voice, respectful of, but not overly impressed with the doctrine of conservatism that rules the scene at the end of jazz's first century. There is little conceptually that separates her from her most obvious models -- Keith Jarrett, Herbie Hancock and Bill Evans primary among them -- yet Allen plays with a spontaneity and melodic gift that greatly transcends rote imitation. Her improvisational style is at various times both spacious and dense, rubato and swinging, blithe and percussive.