Your influence: None.
As an employee at McM, You are a cog in their machine. If you intend to work in a place where you can make a difference, see the fruits of your labor, bring about change, have influence, etc...this is NOT the place for you.
The Computer System: Outdated and frustrating.
McM has a home-built and sorely outdated system. Think black screen and green letters, entering simple commands on the keyboard, and having a narrow and non-intuitive view of all the information you need to perform your job successfully. Information sources are also spread out everywhere - (plan on having 5-8 different programs or windows open at the same time, all the time, just to perform your job). If you like things to be organized, streamlined, and intuitive/natural to use, you should look elsewhere.
Company culture: Fear-based, profit driven.
It's all about the bottom line. Any business is in business to make money, and profit sharing is a great incentive to make employees work harder, but many employees at McM would tell you they aren't positive they'll still have their job next month. At any moment you're only a few mistakes - or a few slowly performed tasks - away from losing your job. The general feel is that you cannot be confident or safe: Don't get too comfortable. Keep working fast and accurately and don't let up. No, you probably won't actually be fired without notice or a chance to improve, but they do let people go pretty regularly.
Upward mobility: Very little
The vast majority of the employees are customer service reps, with various glorified titles. "Business Operations Specialist" or Generalist are titles that just mean "call center rep", "order entry clerk", "e-mail reader", etc. There are some more specialized roles but they are few and far between.
If you're interested in management / promotions, plan on doing the same monotonous work for at least 5 years (not exaggerating) before you think about a management role. McM generally does not promote from within. "Management" is comprised of students fresh out of college that are in the management development program, which is high pressure, "sink or swim". These students come in and either do well and start managing within a year, or get fired. If you come in outside of the management development program, don't plan on being in management anytime soon. There is not really an opportunity to work your way up the ladder here, just an opportunity to keep working.
The Daily Job: Boring, yet stressful
The work is simultaneously boring and stressful. 90% of the jobs in the office consist of doing the same type over and over again. Each individual task is called a "workload" and depending on the department, and the complexity of the task, it should take between 2 and 7 minutes to complete each one. This translates to each person doing 50-150 of the same task every day.
Clock-in, do your tasks quickly and accurately, clock out, repeat.
The tasks are mind-numbing and do not require any real critical thinking, deep problem solving, or creativity. Processes are predefined, and each employee is expected to perform in the same way, with a high sense of urgency, and with very few mistakes / errors. They're basically looking for people to be robots, but they still need humans to do it.