I've seen their stuff. It's only consulting if you count changing the title page of an off-the-shelf report as "custom advice". There is lots of "10 people said this", but the whole thing is premised on the idea that the biggest companies are a) internally uniform in their practices b) an infallible source of "best practice". Great if you like reading 10th grade book reports, not so great if you want to run a business - unless of course you're a mid-manager at a large company looking for check-box validation of what you're already doing.
Working there is the most spirit-crushing experience ever by all accounts. To make the point, there is no consulting division, just teams within sales and research.
You can be on the sales side which involves cold-calling aforementioned mid-managers to flog them reports - think classified advertising sales or encyclopaedia sales for the level of complexity and typical hit-rate. Every so often you get to meet some of your non-entity clients at a conference where you cram them with £50 of food in the hopes of getting a £100 sale.
Or you can be on the research side which involves cold-calling more people, this time to try to get them to participate in research - inevitably the only people who complete the surveys are interns and other junior minions who don't know the answers, and those folks who feed you rubbish answers as a joke.