Avantages
It's similar to working at university. You are on your own and need to be self motivated, but there is lots of knowledge and help available around if you ask for it. You yourself take care of your professional development, you choose the areas that are most interesting for you, in between design projects you have lots of time and opportunities to research, try different ideas and architectures. If you are lazy and not motivated, it's a good place with stable job for you to sit quietly in your qubicle and slowly do routine projects. But if you love the black magic of analog engineering, that is the best place to grow professionally. As opposed to university it is more rewarding in a sense that you see your ideas implemented in real products very quickly. At companies I worked before I had hard times putting my ideas into silicon, the responce was - "we are not a university, we need to get the product out ASAP, we have no time or resources for that kind of innovations and can not take the risk". Well, I guess that is why ADI is so succesfull - because they do have time for innovation.
Inconvénients
As opposed to professional growth, the career and salary growth is slow. Again like working at university, you will get rewarded after a decade or two of succesfull work and innovations, but don't expect quick appreciation of your efforts.