Pros
It's easily one of the better places I've worked at. It's an agency so you're looking at a lot of different projects with the turnaround time being anywhere from a few months to doing maintenance for years (although I think they've scraped most of those longer contracts). You'll get a lot of exposure to different technologies and libraries working here. They stay up to date on new tech and aren't afraid to use whatever framework or tools that'll make their jobs/lives easier. It's a work hard, play hard mentality so they're also foosball masters, and drinking champs.
Cons
It can be difficult to figure out your place at the company, be prepared to deal with ambiguity. That's not to say that career growth isn't possible, you'll either have to work hard and produce results or go out of your way to carve out a career path with the CTO. It's moving into more of a corporate vibe with Deloitte having some influence on KG. HR can be an issue sometimes, but the CTO is receptive to feedback.