This is what I mean when I refer to 3D user interface, where the interface has components that aren’t UI, but in the 3D world. (Above is a screenshot, the UI is different types of outfits for the character and the character is shown as a preview in the 3D world.)
Is developing this type of user interface worth it?
Is it too complex for kids to understand?
Should I just create a regular 2D user interface and disregard this 3D preview idea?
Considering kids aren’t brainless (and this concept already exists in Adopt Me!), it’s definitely not “too hard” for kids to understand. Also, ViewportFrames make this possible and common. It’s a pretty good style to use when showcasing clothing, so I’d use it when applicable.
This way of doing a 3D preview is used in countless games across Roblox and the games industry as a whole; provided your UI is concise, clear and attractive, it can’t really be “too advanced” for average players. For games with complex, confusing UI, look at the Paradox Interactive games (not roblox).
As to whether or not it’s worth it, it’s an aesthetic choice that shouldn’t take you long to code or design, but that’s down to you and the way you work.