This comic is based on real experiences... when playing Heavy and facing the never ending torrent of fireballs I though such strong weapon would have limited ammo and long reload times.... how little I know.
Dragon's Fury have 40 "bullets" and never need to reload. The damage goes like that... 25, 75, 75, 75, 75, 75.. ad infinitum, plus afterburn.
Now, some people say it's not OP if you compare it with the rocket launcher so let me give you some numbers. A direct hit from a rocket does 90 damage (can be less or more depending of the distance) and you have 4 rockets loaded plus 20 loaded, 24 total.
In a solo 1 vs 1 situation, I'd put my money on the Soldier who has more damage and more health, this said...
Team Fortress is a team game so it's common to be fighting multiples, or several people in a row. After dispatching the one enemy, maybe two, the Soldier needs to stop and reload, and he reloads one rocket at time with that sweet, sweet long animation.
Meanwhile, the Pyro just... keep going. The fireballs pierce multiple enemies, put them on fire and has a very generous hitbox.
Now, I'm not saying he is OP yet, but it remind me of the whole Junkrat vs Pharah thing. If you have one hero (Pharah) with superior mobility and high damage, the hero with lower mobility (Junkrat) needs to have higher damage otherwise what's the point? And yes, even with the jetpack Pyro is still clunkier to use compared to Soldier, thou I need to say, not THAT much.
One curious thing I want to point is at some point Soldier had 40 rockets, which made some maps like Dustbowl very spammy. Pyro is basically old school Soldier. I will find very unsual if at least the ammo count of the Dragon's Fury isn't cut down.
Closing thoughts: I think Pyro, specially with backpack, is stronger than Soldier right now unless you are one of those Soldier who are expert a juggling people and very good at rocket jump. Even them you may find the new Pyro isn't the free food he used to be.