In my personal opinion they are a decent engine. Ppl have to remember to read between the lines when some retard opens his mouth about it. They are prone to many issues but many of these soo called "failures" are due to the major lack of knowledge and maintenance. I get decent fuel millage myself on the hwy but in town I tend to drive rather aggressively, hence bad mileage. some one also mentioned filters, I buy them straight from international, $50 for fuel and oil filters. one last thing ppl have to remember is that new emission standards are a big reason for complications, higher injection pressures along with egr treatments are not necessarily good for engines.
A good maintenance schedule along with good filters and oil will go a long way in the life of any engine.