Pros
Not many big agencies that as a creative, let you be yourself. And give you the independence to do so. The opportunities as a creative are in abundance. Amazing clients and incredible briefs all there for the taking. Lovely people. The culture and the atmosphere is both welcoming and comfortable. The snobbery you get in most other agencies does not exist in iris. It's a pretty special place for that reason.
Cons
Not very good at retaining talent. They use undervaluing tactics and aren't competitive when it comes to pay increases once employed. So often lose key creatives. Also can be tardy with career development of key individuals. There's a bit of a culture of equality which is one of the great things about the agency, but also leads to a lack of competitiveness and work apathy or laziness. It can make those who are succeeding with their work feel undervalued. And allow those without drive and ability, get an easy ride and hide in plain sight.