Pros
Great learning environment, cutting edge resources, great people to work with tremendous knowledge base. UOP really has a lot of opportunities and a nurturing environment, but you have to want it. There are a lot of incentive-based opportunities available that will get you noticed. Although owned by Honeywell, UOP has its own company culture, very tight-knit group of scientists and engineers. Having Honeywell as the parent company has its advantages however (stock options). Overall a great work experience.
Cons
Honeywell has somewhat diluted the company culture, many obscure meetings and company philosophies, pay is a little on the lower side, you do have to work long hours to get recognized, and everyone is overworked. People tend to stay in their roles so advancement is somewhat limited.