An enjoyable fantasy romp through multiple worlds (shadows) and delving into a bit of pop-metaphysics, but ultimately lacking the depth that I found in Lord of Light. The first half of the series, dealing with Corwin, tended to hold together better than the books centered around Merlin, which jumped around a bit more. Nevertheless, a good light fantasy read.
The Amber series: excellent fantasy pulp-fiction, set in a unique universe. Zelazny is all about conceptual singularities, playing through them with lots of action, a cynical wit in first-person. Entertainment exceeds continuity (not surprising when writing for pennies per word); but great fiction anyway.