Pros
Although Insight is a big company and has made a few acquisitions, adjusting their culture to accommodate new cultural perspectives and new additions, I have been pleasantly surprised to see a solid, harmonious blending.
Focus on client is key - as in any business, but especially consulting - but I've witnessed a real focus on not overloading consultants or burning them out. I've seen occasional "hot burns" - but they are few and far-between.
Also, there is active concern at the various management layers not to overburn employees. They genuinely care about work/life balance - versus the "lip service" I've witnessed in other companies.
Because it's consulting, you get exposed to a lot of different ideas, methodologies, personalities, technologies, work-arounds, etc. You see *many* different ways of doing things. It really broadens your experience base versus being employed with only one company, one methodology, one technology, one way of doing things...
Cons
It's consulting. There can be a bit of a "revolving door" employment with short-term employees who are looking for a "stepping stone" between other employment. I've witnessed some unprofessional activities by some of the short-term employees (lack of notice when leaving, unprofessional work ethics, etc.) Insight is amazing and takes these things in stride - but I caution anyone looking at going into consulting: be professional; give two-week notice; treat this like part of your career and not a stepping stone.