Vantaggi
They have interesting challenges to work on, if you can beg/borrow/or steal your way into one of them. Somewhere in the company is someone that knows how to do almost anything you want to learn to do, and they will generally gladly talk to you. Whatever your challenge requires, the equipment is somewhere within the company.
Svantaggi
A bad review doesn't mean you did a poor job, it means they A) don't want to pay you what you are worth, or B) want to lay you off. Reviews are consistently distorted in this way (dishonest). The best way to get on the layoff list is to (intentionally or accidentally) challenge some executive cherished illusion. Being hardworking and good at what you do does not greatly matter in determining your career success. They find reasons to differentially lay older workers off, regardless of peer respect or productivity (perhaps a cost issue?).