Chen is FAR stronger in almost every respect now (apart from his Lvl 20 talents).
He can now spec into damage AND survivability. Due to elusive brawler, he is next to impossible to kill whilst normally finishing top damage every game.
Regen build for Chen was nice but grounding brew or consuming flame (bit win more but helps with certain match ups) were better picks. They gave you stronger laning phase and preventing damage is almost always stronger than healing damage (unless you are vs a heavy poke comp, in which case Chen is naturally good vs them anyway).
Pressure Point loss at 16 hurts, it is true. But Lvl 13 Pressure Point is still very good (80% slows from Lvl 13 are no joke, even if you are losing an initial powerful slow).
Element Conduit is really just a win-more talent. If you can take it over the two activatables, you're probably going to win anyway. The power of bolt or hardened is VERY high, allowing you greater outplay potential. His new 20s are nice... but no-where near as good.
He is tankier (because of elusive brawler) and he does more damage (because of Lvl 4 talents and keg cool down reduction at 16). Sure, he doesn't regen much anymore but you don't need it if you play properly.
Granted, I have only played 5 GM HL games with him, but I have won them all. Finishing top damage in all but one and solo tanking in 3 of them.