Pros
I have worked for large enterprises and Arm is actually a small one compared to them. These big ones often have "sophisticated" systems around processes and I haven't found any that fits the purpose. They are usually imagined by someone ignorant at the top and implemented by someone ignorant at the bottom. Now in Arm it is completely the opposite. We have systems, cleverly put together, designed by clever people and they make our life easier. I am in Arm for not too long and I had many pleasant surprises how much effort Arm has put in to make it a good place to be in. And these efforts succeeded. I focused on the general feeling to work in Arm because the specifics will be different in every job/level/position, etc. For me as a seasoned software developer I find that the benefits are top and again I was surprised after joined the company, that the package is actually more than it was advertised. (Ask about FlexPot from your recruiter...)
Cons
I haven't found any so far
