Pros
I worked at the Bothell site (formerly Advanced Microscopy Group) and generally speaking the technical team is quite competent. If you are looking to gain some experience and can put up with the corporate idiocy , it's not a bad place to park yourself for a few years.
Cons
Unfortunately, not all teams are that competent, and Thermo has a problem with firing people. We had the misfortune of having to work with some of the worst engineers I've encountered from their Pittsburgh facility - how these guys managed to ever ship a product, I have no idea. However, my biggest complains are along the line of how the company treats its own employees: 1) I had a child during my career with Thermo Fisher. Despite planning months ahead and putting in the paperwork for paternity (unpaid, FMLA) leave, HR decided to not grant it on the week my son was due. They refused to grant FMLA leave until the child actually arrived. My child arrived 2 weeks late, so during the 2 weeks leading up to the child birth every few days I had a fun call with a droid in Human Resources asking if I want to use up my sick time, my vacation time or come back to work leaving a pregnant wife that couldn't drive herself anywhere for her medical checkups. As a result, my son came into this world with me not having any sick time left to care for him if he was sick. 2) HR would tell you that the vacation policy is inline with what is offered in industry. What they don't tell you is that A) they combined sick and vacation days into a single PTO pool, and in the process most people with any sort of seniority lost "time off". Secondly, this PTO pool is very difficult to use thanks to all the rules added in. It is wiped clean at the beginning of the year and granted in 1/12 increments at the end of the month - so your December vacation allotment is granted on Dec 31st and wiped off the balance on Jan 1st. To "graciously" allow you to use your earned vacation days, HR allows you to go up to -40 hrs on the PTO balance. Rounding errors and such would make it hard to take all the vacation days and also it precludes the ability to take any decent vacation for the first half of the year. 3) I've since found better employment at greener pastures, and shortly after handing in my resignation I received a letter notifying me that our family's (lousy) health insurance coverage will terminate at midnight the day I walk out the door. Every job I've had up to this point covers you until the end of the month (since the deductions from my paycheck had paid for them till the end of the month). They wonder why 50%+ of the staff say that they'd rather work somewhere else for the same pay, and installed a pop corn machine. Too little, too late...