Avantages
I've worked for several large companies before and Arm is by far the most laid back of any of them. The management is very cool and accessible. (I sat next to the CEO Simon Segars at a dinner a couple of months after starting. The benefits are better than average(healthcare especially!) There are also little intangible benefits: farm to table cafe with a private chef on site, funds available for self-improvement, super flexible work schedule.
Inconvénients
There are two main downsides to working at Arm here in Austin. First, no stock shares. Since Arm is owned by Softbank now, there's no opportunity for stock to be a part of compensation. Second, the Arm office is pretty far south. If you live down south that's a benefit. Unfortunately I live north so the drive can be hellish depending on the time.