I'm a huge fan of Critical Friends - if it's set up and well-run. I've been fortunate to have experienced both extremes. This is such a powerful tool for creating collaboration and open reflection on practice but it does take time to set up and structure it well so that a community of learners develops along with a strong community of practice. Trust is absolutely key.
My best experience came from the school in which I was a Deputy Principal a few years ago. I learned so much from creating knowledge with my colleagues and from observing their teaching and learning processes. I also learned to be able to coach teachers to be able to reflect deeply on their practice. The biggest skill I think I learned was to be quiet and actively listen to what they were saying and how they were reflecting on their practice and asking appropriate questions in order to help them in that reflection process. That is something I really want to continue in 2015.
Critical Friends becomes such an important part of the professional learning cycle / Action Research / Reflective Practice that it's power cannot be underestimated.
I'm also quite heavily involved in supporting and mentoring many people online and in person. This is powerful for my own learning development as well. I hope that they get as much out of our conversations and knowledge sharing and creating as I do. My expectation would be that they'd tell me if this was not the case! I need to learn from them too.
The link below includes video clips, etc of the Critical Friends process and would be a great resource to share if you're starting off on this journey.