Pros
I worked in a smaller, more regional branch, initially as a CMT technician and then as a Staff Professional in the CMT group. Overall I have fond memories of the people I worked with. My boss was new to his position but he was fair and kind. Everyone worked relatively smoothly with one another. The work was hard and repetitive but I felt decently well compensated and I was able to earn a level of respect and independence through good work. The 'old guard' near retirement is very competent and provides excellent training.
Cons
S&ME has problems retaining skilled employees and letting go unskilled or unmotivated employees. This is a result of their attitude with bidding on projects, in-which they frequently bite off more than they could chew and needed the manpower, even if it was sub-par. This leaves a burden on the rest of the employees and creates a very hectic atmosphere. I frequently felt under-utilized and despite having experience (and passion) in a very useful, adjacent field I was never considered to move laterally to the relevant group in the company. Don't get me wrong: I understand putting in my time slumping concrete to get to a better opportunity years down the road. But I have to know someone is thinking of me and showing me a timeline or I'll get burnt out and leave the company. I didn't get that from the upper management so I left. I'm not alone in this and I think it's a frequent problem S&ME has with younger professionals. Lastly is a problem that is not unique to S&ME. Profitability is key, and hours for training or more support activities can be frequently neglected. The result will bite them back one day, especially in the lab and compliance.