Pros
This company is very good for the local community. It provides lots of stable, decent-paying jobs with full benefits, and they give lots of money to charity. They also do things like give discounts to areas impacted by natural disasters. The on-site gym and health clinic are awesome, and it's nice to be in an employee-owned company, even if that doesn't translate to actually having any say over how company assets are used. The company also invests heavily in research and makes very high-quality products.
Cons
Many things have not changed at SEL in over 30 years, notably the leadership and management style. It's super hierarchical with a command-and-control style. Even with 5,000 employees, all significant decisions are made by about eight people who got to where they are largely by telling the company founder and president exactly what he wants to hear. For being a tech company, SEL is fearful of change and even technology (for instance, they're completely paranoid about USB memory sticks, cloud computing, or even having a company blog). People are not trusted to do their jobs, and because nobody feels empowered to make a decision, every single issue that comes up requires dozens of meetings and reviews, hundreds of wasted hours, and no actual decision until circumstances force the path of least resistance. Moving ahead in the company is all about tenure and playing politics; talent and hard work count for next to nothing. Those who try to make change or tell the emperor he has no clothes get punished. Employees are also heavily surveilled. In a nutshell, the company culture is defined by fear (on the part of employees) and arrogance (on the part of management).