Avantages
Smart coworkers, plenty of different interests. Company makes buckets of money and plenty splashes over the side to you - most of the time you live within your own means, but about a dozen times per year you're treated like a king. Good Pats/Sox/Celts tickets, great meals, all-company meetings where questions are welcome. You'll get what you think you need for your job almost all the time. Rapid turnover allows you to move jobs when you get bored.
Inconvénients
Pay used to be great and no longer is - raises in-grade are small. About 1/3 of your friends will leave every year. Office environment used to be great, a real "round table" environment where the only change in offices between VP level and peasant level was an extra 60 square feet of open carpet. Now hardly anyone gets their own office or even cubicle. The building they moved to is too small. All of the founders have left. They were good at finding talent, so the company is still healthy, but it's now DS Solidworks, not SolidWorks Corp (primarily owned by DS). SolidWorks employees used to have unlimited decision-making authority - if you disagreed with someone's decision, you walked into their office and they either changed it or explained it. Now it all goes through France and takes a lot longer.