Pros
The coworkers are supportive and are nice. It's a quiet work environment allowing you to think and get your work done. Everyone is willing to help if you have questions. There is occasional in-house training, done by employees who have been there a long time and are knowledgeable about the system. Depending on the manager, telecommuting is permitted. The parking spaces are covered. There is a gym, with shower and sauna, in the building. The company rewards employees with a Christmas party and raffles off generous gifts. You can sometimes return if you leave the company. There are many who have been there a long time. The company participation in the 401K plan increases the longer you stay.
Cons
For IT professionals, it is like working on a contract but being on salary. By that I mean the benefits are mediocre, like when you are contracting and the contract firm participates as little as possible which keeps your premiums high and coverage merely adequate. The dental plan and vision plans are minimal. After you are there a year, you are eligible for 401K. There is a pervasive atmosphere that makes the employees feel as though they are walking on eggshells. People disappear, no rhyme, no reason. Even though who resign are asked to either leave immediately or, depending on the manager, walked out as though they have been fired. This makes it appear to the other employees they have been fired and, since nobody knows why, makes them nervous. There are no "gathering around the water cooler" meetings where coworkers can get to know one another better and exchange information. There's a feeling that you are being watched. Your movements on your PC are monitored, even though many websites are blocked. There are break rooms on each floor that are minimally stocked for those who bring their meals. Eating is not allowed at desks. Cups must be covered and you must bring your own. Dishwashers are in some of them but are rarely used. Coffee, tea and cocoa is provided but no plastic forks, spoons or knives. Salary is just below market. Raises and promotions are hard to come by.