Ventajas
Great set of people to work with. Good work life balance. SW really pampers its top talent. A very pleasant and friendly work environment. A very accessible management who really believe in open door policy where one can walk in with any issue without a hitch. Unless until your job requires to (customer support e.g.) flexible timing is allowed. SW (and DS) is a lot better than any other 3 billion dollar company out there. Like any person, it has grown from being a young company to a more mature company. There are pros and cons to that. Being mature it really weathers downturns in an extremely efficient fashion. In all financial crisis hitting the world since its inception, SW has never laid off a single employee for that reason. Not a lot of companies fall in this category (not even Google or Microsoft)
Desventajas
SW is undergoing a change. Though it can be debated if it is better to change or be stagnant, keep on doing same old and hoping that world around you will not change. It is no longer a startup. It does not provide breakfast anymore. It does not provide company outings anymore. If that is the reason why you work at a company, I strongly advise you to walk away, this might not be the right place for you (Google is the place for you :)). There is free soda and a choice of coffee for you though.