I wonder about this actually...

Thinking of how our parents or grandparents might be able to use a computer just fine but they can't find their way around a flat mobile UI -- Is the Snapchat UI just a new paradigm that we old people don't get? 10 years from now, will this kind of UI design be pervasive?

What if UIs are evolving and we're being left behind?

Yup. 38 here, and I can barely use it. My teenage daughters do it just fine (they were the ones who talked me into signing up). Although I am very technical the UI kills me. As a teen I think there are less mental barriers, assumptions and the like who picked it up just like I picked up DOS and Windows 3.1 when I was a teenager.

I doubt this. I saw Snapchat and thought "okay, this is it, this is what getting old is. There's a program I can't figure out".

Then I asked a 16-year-old niece if she finds it intuitive, and, no, she was as baffled by it as I am. So it's just bad UX. I've spent the three minutes acquainting myself with it since, so now I can use it fine, but yeah, it's definitely bad UX.

I think you're right. I'm 28 and have noticed a lot of people my age complain about the UI/UX. Obviously this is anecdotal but people 25yo and under seem to 'get it'.

I personally like the UI/UX, and think it's advanced. I'm incorporating some of its elements in my own work. I for one am pretty tired of lists, lists, and more lists. I've read somewhere that the UI/UX was built in a 'Japanese style'. I dont know if that's true but it's interesting.

I think where there's room for improvement is just introducing the features and explaining how the unconventional navigation works.

Also, I think you actually validated minimaxir's point. The app succeeded with crappy UI/UX and that sets an example to others: "hey you don't have to build good UX". It's dangerous.