This book has a special place on my bookshelf. It was the second fantasy series I read after LotR. These two are the reasons I love fantasy genre. Since that time no other books forced me to use my imagination to the same extent as Amber. Each book (there are 10) completely changed how I thought Amber world works. Some people feel the last five books are weaker than the first five, but they are still very entertaining (my feeling - Corwin is better storyteller than Merlin).
For those curious how Zelazny planned to proceed: hunt down Amber short stories. They are really short and leave you with craving for more, but the sequel will never come, sadly.
To make a long story short - for those who have not read it yet: what are you waiting for? These are really great.