My big concern with Gartner (and similar companies like Forrester) is that it is ultimately a “pay to play” model.
Not that money explicitly changes hands, but companies that want to be recognised by Gartner have to spend significant amounts of management time engaging Gartner and explaining their product/service (in effect “selling” to the relevant Gartner SMEs).
Some of the most innovative companies don’t have the resources (or frankly willingness) to engage, and will only get recognised “by default” much later in their evolution.
Top tip for companies that pay for a Gartner subscription? Do exercise your right to have a 30 minute consult with the Gartner SME at key points in a selection process; e.g. validation of some of the “unlisted” vendors in your long list (the SME may have a view), and key viability questions to validate your final 2-3 vendors (including licensing model tips and negotiations).
If you are dealing with a “megavendor”, also worth engaging a specialists licensing consultant to ensure you get the right license for your business including growth, and negotiate away constraining terms and automatic annual cost uplifts (often some terms will be removed for the asking)