Back to IT Agile - it has its flaws too, the ones that no one talks about. If you have a business owner / executive team who doesn't understand what Agile actually means but goes by the dictionary definition of Agile - I offer you my condolences ! Been there and felt that, its an extremely daunting task to get anything done with ever changing requirements and expectations - try to raise it and pat comes the reply 'oh, we are Agile, the team should constantly adjust'. It also doesn't work with nascent teams of newbies - Agile relies heavily on autonomy and self organizing teams - hand holding interns or fresh graduates takes its toll on velocity and overall capacity. Retrospection comes with experience - ideas on what we can do better can come about only if the team does know of what else is out there that is better.
High risk sectors like atomic research or aerospace aren't good candidates either - if there are using Agile, please don't let me know, I still have to overcome fear of in flight turbulence :-)