My main criticism of the Rhino UI is that new users are completely lost at certain important things, without going to the forums to ask about it, like commands that don’t have toolbar icons. This is important because Rhino often uses completely different terms than the rest of the industry, like “match” instead of “align” and “polysurface/join” instead of “stitched surface”.
Similarly “one shot snap” things, for example, I still must refer to a forum thread I created once, every time I want to perform a very basic thing like snap to isoparms on a different surface, which requires holding down of control over the snapping options to reveal a whole new set of options, which then you must know precisely where and in what order to click, unless you want them to disappear again.
And filleting, one of the most important things in product design, is hidden under so many different tools, which apparently either don’t work very well, or work but are extremely basic…
…which leads me to actually the command line. That’s the most eye sore thing that tarnishes the entire UI of Rhino, and scares away many new users. Sure, ok, for advanced users, fine. But why on earth would you bury tool options in there in this day and age? I get that’s it’s cheap to develop, but it’s 2019. One would hope to have a proper UI for tools.
Ok, venting over (and I do get that the price of Rhino is very cheap, so my expectations should be tempered accordinly).
EDIT: Oh, also interesting to see some people mentioning wanting monochromatic icons and comparing to Blender, because there was quite a big backlash against this on the Blender forums, and some color is now back even in the default 2.8 theme.
EDIT: Forgot another big thing! When importing STEP/IGES files from a CAD application that works with assemblies, it’s extremely difficult, if not impossible to work with it without destroying the inherent hierarchy in the file. The “block editor” doesn’t cut it and is pretty much unusable from a usability perspective (and possibly even functional perspective, I honestly don’t know).