“I'm basically giving myself a permanent vacation from being BDFL”

Damn dude...

I'm sick and tired of writing stuff like

m = f( <...> )

if m:

    # do stuff with m

Trivial as it may be, I for one welcome this.

Yep, and common for regular expressions. I’d alwayed liked the simplicity of Perl’s “if ($x =~ /.../) {“ and in Python you had to create the match object before you could test it. Assignment expressions should work nicely there.

That's pretty much the main use of the new syntax. When you have a cascade of regexes, it is even better:

  if m := re.match(...):
     ...
  elif m := re.match(...):
     ...

The world is not coming to an end, as some detractors of the PEP might think. The new syntax is a win in a number of cases. Otherwise, you don't need to use it. The concern for abuse is way overblown. I could live without it (voted -1 on the idea originally) but now that it is in, think it is fine.

Many languages solve that with pattern matching, like in Haskell:

    case f <...> of
        Nothing -> -- Handles the problem values
        Just m -> -- do stuff with m

This is, honestly, much better than an assignment expression. Side-effect expressions always bring problematic cases.