Yes I liked it too. I read it within a short amount of time and I don't even read much! The only parts I don't care for really is they talk a lot more about Lucy Mancini and Johnny Fontaine a lot more and also they have that abortionist, maybe he wasn't included in the Godfather movie because of the whole Vincent Mancini ordeal.
Also I didn't care for Nino's character too much either.
I do like the discription of Sicily though, it's almost like you're there when you read about it.