Pros
If you want to work in a place with a team of genuinely engaged people who care about the mission they are performing AA is the place. It's easily the most lovely place I have worked in a 20-year career as a designer. A really strong mission that, if it succeeds (and I believe it will), will change the UK and the world When I was AA I always got the impression they genuinely cared about the staff and did their best to treat them fairly and give a good work/life balance. If you like a challenge and are self-motivated, you will do well at AA, and there is always ways you can help if you are so minded, if your not motivated, though and looking for an easy ride, it is probably not the place for you.
Cons
Because AA is a VP-funded start-up, the benefits aren't amazing. However, they do the best they can with what they have. The drone ecosystem is still developing in the UK, not helped by the CAA, so it can be a challenging and frustrating field. It depends on how much you like trying to change the world for the positive (like I do).