The company I work for uses Scrum, and only Scrum, for all of its IT development projects...and some of the non-IT projects too.
We have 4 week sprints, dedicated Scrum masters, CI processes, CD processes, TDD, burn down charts, velocity, etc etc...
All developers have to attend a 2 day Scrum training course, then a 5 day Agile Engineering course before doing any work in a Scrum.
It's not perfect, but in 6 months I've delivered more business benefit than approx. 6 years' worth of non-delivered effort where I worked before.
The trouble is, that it's easy to do it badly, and REALLY TOUGH to do it well. It takes a lot of effort. Trying to get developers to embrace TDD is a real pain...until they see the benefits...and once converted they never go back...