Pros
Incredibly flexible hours. You get to work directly with researchers every day, helping them solve problems with Zeiss products. The products really are great and the company regularly innovates. Every year expect some new product to be released. Because the organization is so flat, you are visible at all levels.
Cons
Great experience personally and not many cons from my experience. Others complained about the lack of communication with upper/middle management and the unreasonable sales goals. There will be pressure to sell, but that really amounts to simply keeping good customer relationships and competing! it's an incredibly flat organization (you - manager - president), so don't expect to "move up", and the tenure of competent performers is probably 5+ years.