It's a pretty big deal as without an actual JSON data type queries are really parsing against strings for every action, which is much much slower in practice.

Most of the JSON functions added in iirc MS-SQL 2016 really performed poorly and is a significant reason why denormalized JSON data was used very sparingly... with actual JSON data types (assuming a binary deserialized form of storage), then queries and operations against that underlying data structure can run significantly faster.

I've been pretty critical of it since I tried using it for a few things a few years ago... it still worked well enough for the needs of what it was doing, but I'm glad that it's doing better.

For reference, what it was being used for was to semi-normalize most stored procedures to receive 2 argumenst and return 2. All JSON... the first argument would be the claims portion of the JWT for the service, the second would be a serialized typed request object representing the request to the service and the two results are the natural results to the sproc as well as an error result if an error occurred. This allowed for a very simplified API surface (basically 4 utility methods being used for all API calls), in the project in question it was a requirement for data logic to be inside the database, of which I'm not a fan, but it did work out pretty well for what it was. Other isseus not withstanding.