Just when I'm warming to 5.10, comes 5.12!
Perl is far from dead/dying nowadays, with 5.12 being released recently, and the yearly timed-based release plan and all. In fact, just after I start to be comfortable using some of the 5.10 niceties, here comes a whole new version with even more niceties waiting to be explored!
Features in 5.10 I'm using regularly.
Defined-or (if there's only one feature I can have in 5.10, I pick this one).
State variables (love it!).
Features in 5.10 I'm starting to use.
-E switch (but my reflex still says -e all the time).
Recursive pattern in regex (e.g., via Regexp::Grammars).
say() (maybe if I say it often enough I'll start to say say more).
Features in 5.10 I rarely/ever touch.
Smart match (I know it's a godsend, but strangely I never feel the need for it so far).
given/when (I'm sticking with if/elsif/else, especially since given/when cannot be used as an expression yet).
Named capture in regex (yeah, old habits die hard).
5.10 and 5.12. IMO, 5.10 contains more "significant" visible new features for end users (i.e. Perl programmers), especially in the area of new syntax addition. It's 5 years in the making and delivers many features borrowed from Perl 6. But that is not meant to belittle 5.12 which also packs some major goodies, especially pluggable keywords. This one promises to usher us into a world of new syntaxes and mini languages, though it also confirms Perl as being a language that is "impossible to parse" and it surely will pose a challenge/headache for PPI and syntax highlight/Intellisense writers. I look forward to something like a better embedded SQL and templates (using pluggable keywords instead of treating everything as strings all the time).