I think the jury is still out on whether or not the existential operator is too clever for its own good (in particular when used as part of a chained expression).
I suppose if you're using it to make skirting the "Law of Demeter" and thats something you don't want to do it could seem like something bad.
But I'll take "foo?.bar()" over "foo.bar() if foo" gladly.
That's easy enough to remember, though.
I found myself trying to decide whether or not to use it the other day and decided for now it was too clever. So I guess the jury is out in my own head, maybe not in anyone else's.