If you go buy actual objective measure of what people tried to achieve, Shuttle is a failure. They literally drop an architecture, Apollo, that was perfectly achieving what needed to be achieved, namely, facilitate humans to LEO, extreme large payload to LEO and large payload to LEO, very fast payloads for outside of LEO and single shot space stations. All of that existed and was able to be build of the shelf.

Shuttle then took all that money, in turn losing the US the capability to do all this amazing stuff. With the promise that it could then do all those things again but actually do it cheaper.

In that aspect, Shuttle completely failed. Not only did the US lose most of its capability for the next 40 years, some we still have not gotten back. And it did that while costing absurd amounts to develop and then a huge amount to operate, so much that NASA barely had a budget to actually do anything useful with Shuttle. And of course it also took so much time to develop that a whole space station had to be scarified for it.

So really the whole Shuttle program is an anti-achievement, it literally directly reduced the technical capability of a nation and turned it from the best space nation in the world into the second best to arguable being second best.

Technical complexity by itself is not a mark of great engineering, and that's all Shuttle was. In terms of actual objective measure, Shuttle is a failure pretty much every way you look at it. Failure on cost, failure on safety, failure on ecosystem, failure of evolution, failure operational reliability and so on.

Soviets could launch payload and human cheaper to LEO for the next 40 years and only SpaceX brought this back to the US.