There has been a good deal of debate about this flexible service program. YOu may want to search the Shop Forum archives to read the previous discussions. My take on the flex-service system is as follows: You should be okay in the short term (while under warranty) but I would doubt that after 120K miles the engine would be in as good a shape as one with 3K-5K oil changes. Oil and filters are cheap, engines are too damned expensive. If it were my car I'd stick to the old fashioned thinking of regular oil changes.
Hope this helps...Lee