Pros
I worked at Publicis for almost 5 years total. I started out as an intern and a few months later was hired on full time. I loved my experience there for the first 3-4 years. The people were kind, easy to collaborate with, and genuinely cared about my growth as a young employee. If things had continued the way they started, I would've stayed much longer!
Cons
In the last 2 years, however, the agency went through quite a bit of management changes. My boss was let go, and after that, leadership was constantly changing. The global team also started enforcing restrictions on which vendors we could work with as production department, and how much of the work had to be done in-house (even if the work would suffer because of it). It was disheartening to see the decline in quality of work and to watch the agency lose clients. If things had continued in the way that they started, I truly think I could've stayed for decades, but unfortunately by the end, the agency wasn't the same.