Pros
GA-ASI is a very vertically integrated company. As a mechanical engineer, you can easily get involved with both design and manufacturing aspects. Senior management has a good idea of where they want to take the company business-wise and invests in that vision. GA-ASI is privately owned and is not beholden to stock market interests. This gives some stability to a company in the very tumultuous defense industry. After 6 months of working at GA-ASI, you are theoretically allowed to transfer to other departments if there is an open position that matches your skills. However, in practice, HR often does not consider your application unless you have been at your position for several years. Still, if you can meet the right managers and be on good terms with them, the opportunities are there.
Cons
There is a very fragmented company culture...lots of infighting between different engineering and manufacturing groups. There are design-for-manufacturing issues with many of the products. However, many design groups are unwilling to improve their designs because of time or funding. In addition, due to defense budget cuts, the US government has become more unwilling to pay for product improvement, wishing that GA-ASI would just get the products right the first time. This creates a black hole where design and manufacturing problems never get solved. This problem could be solved if design engineering instituted better checking and validation processes prior to releasing a new design. Some of the business processes such as engineering changes are still conducted as if they were from the stone age. This leads to a lot of lost paperwork, whereas other companies have long since moved to paperless systems that can track paperwork in real time. With the defense budget sequestration that is currently happening. GA-ASI has been relatively immune so far, but could face future problems if they do not find new customers for their aircraft.