Pros
People are generally nice to work with and work is very hands on. Benefits are better than average and firm treats its employees well. Working here is relatively secure. Company has moved in the right direction with flex policy and letting employees change jobs internally.
Cons
Some departments work employees like crazy and micromanage. Others are the complete opposite. How hard you work often has no correlation with pay. Generally too slow to advance high performers because many managers have been at the company a very long time. On the other hand, those that become managers quickly are not necessarily qualified and get limited training on managing others. A very big downside of working in a flat structure is your fate is placed in the hands of of one or two individuals that control limited opportunities for promotion.