Koch is a challenging technical environment, if you're working in IT. The company is working hard to get into the current decade technically, so things are moving very fast, which means there's a certain amount of chaos in the environment. To be successful here, embrace the change and the chaos. It's definitely challenging, and not the place to work if you want to do the same thing every day.
The high rate of change means that there's a lot of uncertainty in the environment. Lots of reorg to try to keep up with the changing technical landscape. That can be disruptive and add time to the day just to keep everyone on the same page.
Another potential con for some people is that this is not a coastal style workplace. While there is some flexibility depending on what you're doing, in general you're expected to work from 8 to 5 and to be in the office every day. For me, that isn't a big challenge, but I've heard some of our employees who've worked at more liberal workplaces complain at times that the Koch environment is just a little bit 80s in terms of work practices.