Pros
I enjoy the productive and friendly environment at F5. The level of cooperation, both intra- and inter- team, is really outstanding. While the company is growing rapidly, there is still a sense of making an impact as an individual. For many, seeing the results of the work well done helps deriving a great level of satisfaction. The compensation is competitive, the growth opportunities are plenty, the work environment is comfortable (larger working spaces, remote access, etc.) and there is a variaty of nice perks available (depending on the location). No wonder many people stick with the company for very long time.
Cons
Some growth pain does shows up, but that is a good problem to have. The products are large and complex, which may represent a significant challenge for the new employees. The flip side of this is that the company encourages the employees to stay longer; obviously, the management understands the cost of bringing the replacement up to speed...