The pay is not great, and you can end up with someone being promoted to the next grade earning more than what someone who came in at that grade. It is essential to find it how much you are worth and negotiate on that basis. Don't expect much of a pay rise beyond standard living increases.
The company has a number of employees who lifers, who get promoted based on years worked than competence. As I stated before if you like to just plod along it is great for you, but for those who are more ambitious, the lifers can be frustrating to work with. Also, as they don't move to different jobs they present a layer of management that will be in post until they retire. Within 10 years the company demographic maybe quite different with those lifers having retired. This may present the company with an interesting time for knowledge retention, but provide more opportunities for those that want to progress.
There is a resistance to change which is proliferated through people working on the same projects for so long. More movement is needed to increase use of best practise.
While it is touted that there are three strands to progression/promotion. It is difficult to identify who is on which strand. And how someone progresses on a non management strand is vague/not communicated. The actual practise and implementation of the policy is unclear and to my knowledge untested.