Pros
HostGator is a great company to work for. While working at HostGator.com, I was able to boost my abilities with Linux by performing in both their Linux Support and their Migrations departments. These departments dealt heavily with not only their server support (Linux Support), but also with customer code, and application support (Migrations). This company is a great place to go for any aspiring administrator, as you can easily learn more than what you would think starting out at a hosting company. There are multiple departments where anyone with technical ability can easily excel. Their monitoring department, for example, is a great way to boost skill with regards to load and I/O issues, and anyone who would like to know more about a particular aspect of systems administration could quickly change departments and learn the aspects they were interested in.
Cons
One of the downsides I can say is that the company needs a bit more inter-department communication. Sometimes there are some issues from management in departments, and changes may be "pushed out" without many employees being aware. Additionally, even though you may be skilled in a particular field, if you are in a particular position, you will be limited to that position. That was one of the issues I had at HostGator.com, as I was able to help out every department, however I was responsible for a particular department and it's work.