Well, he can't have all those buffs at once. If he unlocks the Backburner, an alternate flamethrower awarded for getting 20 of the 35 new achievements, he'll be just like the Pyro now, only with 50 extra health and guaranteed critical hits when flaming enemies from behind. The drawback? He doesn't get the other buff the regular Pyro's about to get. And it sounds awesome.
The Pyro can now right-click to blast enemies, rockets, grenades, stickies and even uber-charged players away from him. He can send Soldier's rockets right back in their face, keep Demoman's Stickies off friendly Sentries, split Medics from their patients to break their invulnerability. Knock people into ravines, shunt them off capture points, set them alight then push them away from medkits. Valve say they still don't know how he'll fare against Demomen and Soldiers with this ability, but they had so much fun with it in internal testing that it had to stay.
One thing he can't do is blast-jump. Designer Robin Walker says they experimented with this, but found it wasn't as fun as it sounded. They tried relegating it to an unlockable weapon, but then players got confused about what the air-blast could and couldn't do. So it went, and honestly, if you think the Pyro still needs a buff after this lot, you just flat out suck.
I mentioned the Backburner, and we've already heard about what the Axtinguisher does, which just leaves one unlockable weapon, glimpsed in yesterday's superb Meet The Sniper video. It's the Flare Gun, and it's tricky to hit with, but skilled Pyros will now be able to ignite enemies from afar. No word yet on reload times, but Flare Guns tend to only carry a single flare in the chamber, so rate of fire will likely be the primarily limitation.
But soft! There is yet another cool change in this update. Unlike the poor Medic, who had to earn every single one of his often absurd, counter-productive achievements to receive his ultimate unlockable weapon, the Pyro only needs 10, 15 and 20 respectively for his new toys. Since there are thirty-five to choose from, this means people can leave the silly ones alone if they don't fancy grinding them.
The Pyro achievements also look generally easier than the Medic's, so if you then cut out the fifteen hardest or silliest, unlocking all the new kit is very doable even for casual players.
The only bad news is for Spies, who aren't going to be terribly effective once half the enemy team goes Pyro to try out the new abilities. At peak, 40% of all players were going Medic when his new changes came out. The Pyro's are far more attractive, and the biggest change is one anyone can try right away. Expect nothing short of a 24/7 inferno.
The changes go live on Thursday, probably in the evening UK time. This weekend, Team Fortress 2 is free for everyone, so if any of your friends are still unconvinced, get them preloading now (Steam required) so they can join you in on the flamey-blasty-axey action.