Pros
#1 is a chance at a jackpot. We're pretty sure ST is going to be sold off the day Dr Laird decides to retire and wants to cash out. When that day happens, your options vest. All of them. Saying that ST is a relaxed environment is putting it lightly. You actually don't even have to do a lot of work at ST. Spend your hours playing darts or switch. Nobody cares. One solid contribution to a project will get you a promotion no matter how many months you spent tweaking some GNN when a simple SVM would have done the job (you know who I'm talking about). And if you have soft skills, they will take you far at ST. Even if you aren't very good at what you do. If you kiss up to the directors enough, you will always have a seat at the table. My advice is to connect with the chief scientist on social media and like/share everything he posts. Go on amazon and give glowing recommendations of his books. He'll greet you by name in the hallway after that.
Cons
#1 is layoffs. Its just how this industry is. One month there is a ton of work on contract and the next its dried up and we have to lay people off. And you won't be asked to come back because there is an unending supply of fresh college grads who aren't burned out. #2 is we have zero tolerance for politics. If you are the type of person who wants to discuss politics at work, be forewarned that you will eventually get reported to HR for that crap. Frankly, most of us find your novice-level understanding of things annoying, but a few in the company who will put in serious effort to get you fired over it.