Pros
Generac depends heavily on the individual efforts of its workers (read tribal knowledge). You also get exposure to a large variety of manufacturing methods. On a related note, the project content can be quite diverse. So, if you're an enterprising self stater,you can build up a resume quite quickly. Additionally, since the turnover is so high, it's easy to find good references. Generac is a good stepping stone. By and large, the people you work with are knowlegable, dedicated, and friendly. The environment itself is enjoyable. Although being the new guy on the block can be difficult, after a 1-2 years, you'll find your part of the fabric of Generac (there always seem to be new people arriving). Generac can be a rewarding place to work, but you had best be happy in the position you hire in as because few advancement growth opportunities exist in product development. That also means you should be sure to negotiate a starting salary that you're happy with as well.
Cons
First, be aware that Generac has a very old school culture. If you work for Generac, your going to wear a tie. Second, If you're in product development, there is very little room for advancement. Generac doesn't groom or develop internal candidates for management positions in product development. Although, I find that this statement isn't true on the manufacturing side of the business. When I left, Generac had hired about 7 new product development managers off the street - not one internal candidate was promoted (and a few talented individuals do exist). Last item, the Generac insurance is difficult to do correctly (worse than average). There is a price for having cost effective health care. Plan on getting to know your administrators.