There's Big-A Agile and agile. The manifesto is really the latter, the former is a set (different depending on where you are) of very specific practices that neglect the principles in the manifesto (though, typically, they were derived from them originally).
Read SAFe Distilled or SAFe 4.5 Reference Guide for what happens in large enterprises (god SAFe is a fuck up). It consists of some good ideas, but also some very explicit practices that don't help in every effort (and sometimes hurt). It is literally the opposite of Agile, which is supposed to be about flexibility.
If you want to hear about its "success", just remember it was used for F-35's software...
Big-A Agile is based on the belief that adoption of practices is sufficient, and that deep understanding is unnecessary. This is the realm of cargo cults.
