Pros
Gallagher is a successful, rapidly growing company that has seen frequent M&A recently. It overall has a stable vibe with good organizational structure, value for teamwork and individual growth, and good benefits. While its largest business area is insurance and risk management, other innivative service areas are growing. Especially if you are part of an established business line, the company offers security, great client relationships and strong client-facing processes, and a friendly, collaborative environment with growth opportunities.
Cons
Organizations that are acquired must transition their brands to Gallagher, a necessary process but one that from my experience can be challenging for acquired businesses that need to change their processes. Public image is still fairly conservative--marketing or sales may find the company not always very "cutting edge," although the company is working to evolve in that area.