I worked at McMillan full-time (More than 10 years)
The agency was founded in 1996. So it is young enough to be fresh, exciting and open to new ideas. But it is established enough to have a solid HR function, well-trained and supportive managers, and an excellent work-life balance. As an agency, the clients' needs can often tip that balance during busy times but the agency is very accommodating to balance things out appropriately. It is a very fun, laid-back yet professional environment. And with clients across the US and Europe, there are opportunities for more global exposure--and from time to time, travel.
The only cons I can think of are actually consistent with any creative agency of that size (80 people, +/-). Internal communication can be challenging and the inherent 'tension' that can exist between clients and creative pops up now and again.
Advice to Management
Continue to nurture the amazing culture that exists. Develop talent from within the ranks.
I applied online. The process took 2 weeks. I interviewed at McMillan (Toronto, ON (Canada)) in March 2016.
The interview was done through Skype and was very straightforward with no BS. The questions were mostly about why I am comfortable working with B2B clients and why I'm interested in moving to Ottawa. The interviewers were kind and warm, not intimidating at all.