Pros
Pay is fairly good, Office and the people working there are competent and nice people. Fairly good PTO policy, Overall project being worked on is interesting and has generally positive societal impact.
Kontras
TNS is a very old-school company, and there is a lot of expecting people to be able to take long calls at all times instead of using chat or email to solve problems. Structure is very heirarchical, and teams are often siloed, with individual contributors actively reprimanded for communicating across team boundaries. Ground-up innovation is discouraged in favor of top-down central planning and secret agendas. LOTS of company politics - many senior personnel are unqualified and clearly only in their positions due to nepotism or tenure. Work on client requests is often delayed or not even delivered due to problem individuals acting as bottlenecks. Senior management seems to have no control or power over these individuals. HR seems to look down on employees in other offices, and has suddenly changed or not delivered on promises for employee benefits. HR will also not accommodate LGBTQ individuals unless strictly legally required to. I would recommend staying away, but they have outsourced all hiring to India anyway.