Pros
Flexible working- can be good if you have children or a medical condition. Easy work which can provide you with an easy life. Not too much stress.
Cons
If you are at a more junior grade, you will either find yourself overworked or under worked. The problem is, that there are so many people at the HEO grade who are under appreciated, not communicated to properly and are just seen as tiny tiny cogs in the larger machine. While that may be indeed true, the vast majority of the work is under challenging and underwhelming. Don't be fooled by the job adverts which may encourage you to join the department on the premise that no one day is the same and you will be constantly challenged. While this is true for certain business areas including comms, private office and strategy, for others this is far from the case. There is a great emphasis on how the department can make things better for all the staff but it is a very hierarchical organisation, that is not very lean. You are often very in the dark about key decisions which makes it harder to do your job properly. Never say you are going for a promotion as there will be some in the higher levels who will actively discourage you and tell you that you are not ready. There is not much mobility in the organisation and there needs to be key changes.