I read just The Godfather, Omerta, The Last Don and The Sicilian.

Omerta and the Last Don were nice to read, but I really didnt enjoy them.
I missed the Quality like The Godfather had, it is hard to explain, its just the feelings and thoughts I had after finishing these two books.

The last one was the Sicilian, already a bit unsure about spending money on further Puzo novels, I really was impressed.

The Sicilian is one of the best books I ever read - it describes the life in Sicily very detailed, without glorifying it nor the main person.
It shows also the weakness behind Sicily and its traditions.

I would everyone suggest to get Sicily - its really worth

P.S.:
I am no literature critic, so please dont measure my words too hard