Pros
Gate One truly does have a fantastic culture and genuine desire by almost everyone I have met to help each other out. There's very much a "work hard, play hard" mentality within the firm - with an annual international team event, quarterly away days and other miscellaneous team events. In my experience at Gate One, I've worked alongside Big 4 / Top 3 consultants on incredibly interesting pieces of work for global clients. For a boutique consultancy, Gate One has a fantastic industry reputation and we have the opportunity to work on interesting projects for large clients. I wouldn't go back to a Big 4 company - my work / life balance is just too good here, and the pay is also much better.
Cons
Not necessarily a con, but it will be interesting to see how the culture develops as the company grows - right now I think this is Gate One's biggest asset.