@Razh:
The bigger problem is that he can't seem to deactivate G4 whenever he wants to. So no spamming like the other two. When he's using it, he has to be sure his enemy is going down. As it is currently, G4 is a gamble. If there was nobody around, Luffy would be a goner now.
He's probably going to work over those cons with time, same as with previous Gears.
I actually hope he won't fix it completely, just adjust the time limit closer to old Gear 3rd to not die in 1 vs 1.
@Demonicpoodle:
He knocked out tens of thousands of fishies willfully. That's tapping into it. Other than that, I don't know what you can mean.
And I actually just took the time to process it but it is a VERY VERY GOOD thing that Haki is limited. This will raise tension, make battles more interesting… I'm all for it!
And Oda is of course driving the point home that Luffy always has a long way to climb up the mountaintop, and increasing his Haki stamina will of course factor in to that.
People with CoC have larger reserves of haki. So either Luffy doesn't know how to tap more of it or Gear 4th simply takes such ridicilous amount of it, then again Luffy had been using haki already all day before he even used Gear 4th.
CoC could also be one factor why DD is not dropping yet.
Overall I don't like how haki is used like any other shounen mental resource, it doesn't really change anything really whether it has a limit or not as they get fatigued anyway.