I dont think it ruined the trilogy, but it definatly wasnt as good as the first 2. The plot was too confusing for me, 5 million old guys who looked the same were all trying to kill Mike.Sophia Coppola simply cannot act(although she can direct quite well)and Andy Garcia was not the right man for the job,as you can hear his Cuban accent numerous times.I think the ending was a fitting way to end the Corleone saga.