Pros
Arm is one of the only places I've worked where people are truly valued and cared for as individuals. This makes coming to work every day a pleasant experience. Additionally, the compensation and benefits are outstanding relative to the competition.
Cons
The company is based in the UK and much of the decision making doesn't happen in the U.S. It's important for those considering working at Arm to know this up front. It's not necessarily a bad thing, just something to be aware of. Additionally, Arm is a collaborative company, which can be a positive, but it can take a long time for decisions to get made with much back and forth. Finally, while the pay is very good, there really isn't a mechanism in place to reward high performers vs. average performers. The vast majority of the company receives the same performance rating and bonus, resulting in being discouraged to go the extra mile.