I think they might be accurately rated. If they were underrated perhaps they would have flourished after iPhone/Android came out (more for the coolness factor than the utility factor, since on mobile they have the issue of something being blocked by your finger, which I think limits it but isn't a dealbreaker). However, donut chart menus haven't been catching on. https://news.ycombinator.com/item?id=39206966
I think they're cool, and that's about it, that the Fitts's Law benefit is too small (as argued in the thread I linked), and that the coolness factor fades fairly quickly for most (though I still want some sometimes).
We performed a controlled empirical comparison of pie vs linear menus in 1988, which we presented at CHI'88 and published in the proceedings. It showed that pie menus were 15% faster than linear menus, and that they had a significantly lower error rate.
An Empirical Comparison of Pie vs. Linear Menus. Presented at ACM CHI’88 Conference, Washington DC, 1988.
What does this mean? Should we program pie menus into our bitmapped window systems tomorrow and expect a 15–20% increase in productivity since users can select items slightly faster with pie menus. Pie menus seem promising, but more experiments are needed before issuing a strong recommendation.
First, this experiment only addresses fixed length menus, in particular, menus consisting of 8 items — no more, no less. Secondly, there remains the problem of increased screen real estate usage, In one trial a subject complained because the pie menu obscured his view of the target prompt message. Finally, the questionnaire showed that the subjects were almost evenly divided between pie and linear menus in subjective satisfaction. Many found it difficult to “home in on” a particular item because of the unusual activation region characteristics of the pie menu.
One assumption of this study concerns the use of a mouse/cursor control device and the use of pop-up style menus (as opposed to menus invoked from a fixed screen location or permanent menus). Certainly, pie menus can and in fact have been incorporated to use keyed input [7] and fixed “pull-down” style presentation (the pie menu becomes a semicircle menu). These variations are areas for further research.
15% improvement in menu selection is an absolute game changer for professional menu selectors who spend over half their workday selecting items from menus. Unfortunately, very few users are menu selection professionals, and such professionals might see power gains than average users.
Task completion speed would be a better measurement, to capture the effect of the pie menu interfering with the main task by temporarily obscuring it from view.
I'm neither a professional mouse clicker nor professional menu selector, yet I and a lot of other people click mice and select menus all day.
For example, there are many professional, indie, hobbyist, and ametuer people called "artists" who use pie menus in tools like Blender and Rhino/Grasshopper and Maya all day, and it saves them a lot of valuable time, and vanishingly few of them are actually professional menu selectors.
And thanks to being "self revealing" and supporting "rehearsal", pie menus make it easy for novice menu selectors to become expert menu selectors, with a smooth learning curve.
The idea started out great but hit a wall every time you tried to gesture near an edge.
It also felt as though you were playing Witcher 3 casting spells...