Pros
Gartner is well-regarded in the IT industry primarily for its research and benchmarks. Almost every CIO has heard of Gartner and a majority of them have used its products, including consulting which is its relatively lesser known line of business. Like many organizations Gartner has really experienced and knowledgeable people. Gartner's value proposition includes "we have people with gray hair and scars who are just like you". In other words, most of Gartner's key employees have had leadership positions in IT. So years of experience in the IT industry is the most touted credential.
Cons
Years of experience in the IT industry is the most touted credential. So if you are a really smart young professional with karate chops and innovative ideas, you'll find a hard time getting respect even if you have hard analytical skills and a business school or engineering school pedigree. On the other hand, if you have those sort of credentials you are unlikely to end up at Gartner. Remember, IT leaders have this "blue-collar" mentality and a dislike for smart innovative types.
