Avantages
I worked at COMSOL a few years, and the biggest pro of my entire time with the company was walking out the door on the last day. Could never bring myself to write one of these, but I see that former (and even current) employees have done a very admirable -- and truthful -- job of it. Don't be swayed by the few "postitive" reviews you see on here -- I know from my time with the company that they were VERY likely written by the litmarks (you probably shouldn't have been asking around if it's possible to remove bad reviews from here, just FYI)
Inconvénients
Nepotism. If your name isn't Littmarck and/or you're not Swedish, you won't be respected here. No matter what department you're in, your managers won't have any say in how things are run -- instead, litmarks will be making all the decisions, no discussion, no negotiation -- and often these decisions won't make any sense. Too bad. Deal with it, put your head down and don't question your betters. It makes for a very toxic work environment, and not surprisingly, not many people stay for more than a few of years at the company (unless of course you're an expat). Managers have no qualms talking about you behind your back and talking to you about others behind their backs. If you find yourself here, my advice is to not rock the boat -- and get out as soon as possible.