I research copiously before purchase... then, I expect things to work intuitively.
My AAS was in computer programming for the human interface (Computer Program Application Development), and so I have a firm grounding in how interfaces should work. It transfers beautifully, btw, to analog vapes as well, as intuitive interface can be as elegant as the Vapman's, or as befuddling as.. well, I haven't bought a befuddler yet, but there are some, I've heard.
If I can't just pick it up, figure out nearly instantly where/how to load it, and how to use it (turn on, get vapor, set temp, etc.), then I consider it a failed design.
This applies not to just vapes, btw. When we first got our juicer, I had it up and juicing before the boxes were empty. Elegant design.
Yes, I too will slap forehead, read manual (I'll skim the Spanish version sometimes...), and then try again.
Oh! our rice cooker... got a fancy one with fuzzy logic. Not entirely intuitive. took me a couple of trips through the manual to be able to do whatever I want with it. I still occasionally have to refresh my memory of setting up breakfast in it.