Pros
I have only been an employee with the new organization since coming over from Schering-Plough so my impressions are limited. They have been pretty good about communicating their intentions with the integration. I had previously worked for Merck so I've known the organization. Benefits appear to be on-par with most industry leaders. Management is competent and the leadership is fully aware prepared to meet the many challenges that face the industry and the company in the coming years.
Kontras
One word, Process. It defines Merck and although process can be necessary it also stifles creativity and risk taking. The organization appears to be very cautious especially in the wake of the Vioxx and Vytorin/Zetia debacles. The company is massive with the combination (currently 100K employees). Corporate politics is already rearing its ugly head.