Pros
Arm is a unique company as it licenses its technology to nearly every major chip vendor in the industry. It's hard to name a semiconductor or electronics company that does not use Arm! I tell my friends that working at Arm is like buying a mutual fund instead of a single stock: our impact is far wider than any single company making a single product. This means we have great view of industry trends, are diversified across many markets, and have great connections across so many critical companies. Arm's culture is open and collaborative. Friends who have joined from big name tech companies have marveled at how different an open Arm is.
Cons
We work hard and as a global company you need to be prepared to work across the world with different time zones. For me this is a huge positive and broadens our connection to the industry worldwide, but you just need to be aware of that.