Pros
Has a good reputation as an donor, but that makes you really worry about the quality of the rest of the them. Has good political support and a large budget, with a good network of offices globally, so the potential to do great work and have an impact is there.
Cons
Dfid is just not skilled to deliver. We use consultants constantly to do our thinking, and the usual suspects to deliver the work. The organisation culture is awful, with the worst attributes of hierarchy (opaque decision making, lots of sucking up) combined with it being really hard to get things done and collaboration across the organisation is awful, people spend most of their time trying to slow down or block other colleagues, especially at HQ. Poor programme management, and a technical staff who are mostly jargon filled experts with little realy grasp of evidence, effectiveness, programme design and delivery. Add to the mix soe really dreadful managers, this is a super disappointing place to work.