I’ll be honest. I consider AMS Euler to be a gimmick. Yes, real books by serious mathematicians have used it, but it’s so non-traditional that it has not been broadly accepted. (Zapf is a real typographer of course. But the project, to me, is more of an exercise in avant garde typography than one to supplant “standard” mathematical type.)

I think that depends on whether you want your stuff to look like some definition of traditional.

The equations in AMS Euler look good to me. [1]

[1] https://en.wikipedia.org/wiki/AMS_Euler#/media/File:AMS_Eule...

They look terrible, in fact. This is no way to typeset equations. (For example, variables should be set in italics.)

Variables have their own style here. Compare i sin y and the difference between the variable i and the i in sin.

Yes AMS Euler is very nontraditional as mathematical typesetting goes — to put it in terms of Zapf's oeuvre, it's not Palatino or Optima but rather Zapfino. :-) Looking at what was written/expected before it was created, it can probably be seen as somewhat of a disappointment.

But it was created to mimic the style of mathematicians writing by hand on a blackboard, and I must say that in the book Concrete Mathematics (reading which was, in retrospect, one of the highlights of my life) it works very well, going well with the book's conversational style, the irreverent margin graffiti by students, etc.