Pros
In Canada they offer decent health benefits like extended health, dental and vision. They also give a free birthday day off, which isn't discounted from the annual vacation allowance.
Cons
Having moved to GroupM Canada from the same agency family in a different country, I found GroupM Canada to be very behind and really undervaluing their employees. They gave me a much lower pay than that which corresponded to my level of experience. I only took it because I was worried about being unemployed coming from another country. I had to work wild hours without any remuneration for the extra time. Some days I would start at 5am and end at 8pm, some days I'd start at 8am and finish after midnight. They said they would give me time off in lieu but never did. I only stayed for 6 months and ended up finding a job that paid around $30K more. They also made promises of work on different accounts, and variety of learning, experiencing other channels, etc. Never happened. Zero development in the whole time I was there