You hear it all the time, yet nobody takes a stance - max lacks consistency big time. Whenever I compare max to some other software, it's always the biggest difference. There seem to be no standards, design manuals or even cooperation whatsoever, implementation details of similar features are different across the application, you sometimes get the feeling they are parts of different softwares in one package, sticked together in a haste. And it's a pity.
The interface is not consistent, the behavior is not consistent and I find myself doing things expecting some behavior that is common elsewhere only to find out 100th time it doesn't work and thinking 'oh, right, I have to do it different way here, silly me' - and this is after almost two decades with max.
There's Place Pivot Surface in the default quadmenu, when I first saw it, I was happy, now I don't use it because it doesn't work with the regular Edit Working Pivot mode which seems to use a different working pivot - hell if I know, instead of finding out, I stopped using it.
There's point-to-point edge selection in the UVW Unwrap modifier which works COMPLETELY different than the so-called point-to-point selection in Editable Poly (by the way I hate that one, it's awkward and weird and whenever I try figuring how it works - and that it works better if I deselect everything first so as not to trigger ring selection - which beats the purpose completely, I end up selecting by clicking instead).
Some spinners are sticky and keep their last input value (editable poly, mostly), some reset to default value each and every time (editable spline mostly, for repeated operations you have to put it in each time).
There are also Sticky Keys that were excitedly anticipated before max 2008, yet nobody uses them now as they are limited to a few hard-coded editable poly functions and you cannot use them anywhere else - and nothing changed since they were added, they are mostly forgotten.
There is the super useful Tangent Handle sub-object mode that allows mulitple tangent manipulation in Patches which is not in Shape objects.
When you click subobject icons holding modifier keys in editable poly, you get converted selection, which doesn't work anywhere else (say editable spline, often find myself trying it there).
Editable spline has divide for segments, which would be very useful if they could be slid, pinched etc. in the same way that edge loops can be in Editable Poly.
There's Folder History in some dialogs (Open Script) and not in others that are otherwise almost the same (Run Script).
Window/crossing depending on selection direction turned on? Well, it only works in the viewport, doesn't work in unwarp, when selecting nodes in MCG or basically anywhere else. I know it is that way, yet almost every single time I find myself doing it out of habit, before it dawns on me that it won't work that way...
Some operations have progressbar, most of them don't, some display their own, some use the prompt bar for that, others output text there instead.
Units of axes in the graph editor are system units, not display units, happened with a few modifiers in the past, mostly fixed, but still lurking in unexpected places.
After all the updates to spinners, MCG still comes with spinners that are not draggable and don't zero out on right-click.
All the code input windows are different, Script editor will use syntax highlighting and colors, newScript() window will only respect the background color and nothing else, MAXScript Listener comes with its own set of colors and shortcuts, and then there are Script controllers with their own pure-text fields.
Some operations allow you to navigate the viewport in the process, for some of them you have to stop the tool first, otherwise the tool effect will disappear - you will only find which are those when you try for example rotating viewport.
Many of the ribbon tools are only one-way, i.e. when you set the value elsewhere, it won't change in ribbon, while in the rest of the interface it shows as soon you change it.
Changing the material is undoable, changing wirecolor not.
Z to zoom extents? Works in viewport and MCG, doesn't work in Slate Material Editor (Alt+Ctrl+Z? WTF?) nor in Particle View - and Trackview? Better forget that one for good...
Want to change Render Sample Size of material preview in Slate? Oh, you have to switch to Compact material editor first and in ITS options change that, then switch back, same with other settings.
Global Search in viewport is different in looks and behavior department than the search in MCG (in Slate and Particle View, pressing X switches to main max window instead to make matters even more complex).
Some of the menubars (Particle View, Script Editor etc.) respect windows style, some are completely different (main menubar still has the gradient background as a remnant of the past while the rest of the UI is flat).
There are even some gradient style aqua buttons still scattered across parts of UI that were new few versions back and untouched since like the Template Manager, and even all-white (despite dark UI) gradient style 'Customize Ribbon' dialog (the Communication center and QAT don't fit rest of the UI either).
MCG, Particle View and Slate Editor use the same SDK for nodes yet they use different shortcuts, look different and behave slightly different, when people complain about something, it gets changed in one area and remains unchanged in the others.
There are multiple slightly different floating tear-off UI parts, ribbon parts show the handles only on hower, they're almost black and come with an additional button to 'dock it back', extended menus come with a windows-themed titlebar with a cross only.
Even if you have Caddies disabled, you get manipulator caddies when Select and Manipulate mode is active.
There's only one of each for Save Active Perspective/Ortho View in both the viewport menu and menubar Views menu, yet you can save multiple configurations in the Viewport Layout Tabs... it's a slightly different functionality yet still the only way to save multiple.
There are many functions that only work under the right circumstances that are hard to guess if you don't already know them. Very little in max is actually predictable. I could go on but I'm already tired just from thinking about it.
These are all things people were complaining about before, nothing new, nothing fixed either. And everything goes against the notion of max offering a consistent and predictable experience - changing those things one by one will help a bit but won't change much unless it's applied across the application and for every new or changed feature.
