Pros
Very strong Learning and Development offering; you're encouraged to take out time to develop skills through internal, other civil service, and external means. You have the opportunity to work on a range of projects; colleagues are very happy for you to get involved in their work if it interests you or you want experience in their area.
Cons
It's extremely badly organised, both in terms of individual workstreams and on an overarching level; lines of/channels for communication are not efficient at all, so there can be a lot of confusion which results in needless, frustrating blockers coming up time and time again. Big egos are very common everywhere you go; overly bureaucratic managers seems to stifle your efforts at doing good work with pointless, unproductive nitpicking. Most senior colleagues are uninspiring and lack rigour; inefficiencies and limits clearly come from the top down. If you are a very driven person, you won't find likeminded people too easily - people seem to just go through the motions (whilst thinking they're the best thing since sliced bread for it). There's a widespread lack of interest in doing anything cutting edge, and most projects are very cookie cutter; there's little opportunity to bring new ideas, methods, etc. which would benefit the project deliverables at hand or the organisation overall. Overall, the stereotype of the civil servant (someone who drags their heels whilst not really dedicating themselves to their work, and is more interested in the cosiness of staying within their comfort zone and receiving a stable, secure career in return) has been frighteningly accurate everywhere I've been here.