Pros
The people (staff) that they hire at McMaster-Carr is great. Great benefits and 100% tuition reimbursement up to a Masters degree. The pay is well above industry average. If you enjoy coming to work and getting paid well without ever getting promoted or furthering career goals then this is the place for you.
Cons
Where to begin.... You will not receive credit for any positive work you perform and your errors or 'credits' will be highlighted to seem like the end of the world. The work is monotonous and is ergonomically terrible for your body. Your yearly review is based off of what your supervisors remember you have done and a few things they'll make up to fill space. In my time at McMaster-Carr, my reviews referred to the last month of work leading up to the review despite the projects and other things I had accomplished in the year. There was no mention of those things. You can perform the same work as a Management Trainee and get zero credit for it, if the MT provides your same results they will be seen as the next great hope for the company. Employees are treated like cattle or cogs in a machine, easily replaceable and largely unimportant. No transparency from upper management down to the staff. People get fired all time for seemingly no reasons. People get promoted with no qualifications. It's all about who likes you more. Raises are based on whether or not the upper management team likes you. It's all about perception and not actual production. You just have to look and seem busy and important. There is no reward or compensation for doing exceptional work. Additionally, get all thoughts of promotion out of your head. Some people get moved around through different departments, but again it depends on how much upper management likes you. You could end up in the same department doing the same job for 7+years. The work schedule is not fair across the operation. If you work in the office the hours are not as bad as if you work in one of the downstream departments. Some people come in at 6am and leave at 3pm. Others come in at almost 11am and leave at almost 8pm. You can and will get stuck on a terrible shift.