I think Pyro is the easiest class to play next to Heavy. Setting ambush with the class is rather easy. The guy comes with 175 HP BUFF-less which is sufficient (150 would be better TBFH). Thinking the Heavy is 300 HP this is damn good HP.
You just rush at your opponents and set them on fire, and just keep at it, try to ambush them. Do occasional spy checks. I wish they'd nerf the class a bit. At least just make it harder to master. Anyone good with the spy can literally own with the pyro.
No, no, no, no and no. D:
Its adorable you guys are playing this game for the first time, but please, you really don't know what you're talking about. The Pyro needs 175 health. He dies easily to almost everything. A competent Soldier, Demo, Scout, or Heavy owns him any day. He has to rely on ambushing. It has a reputation of being a noob class but it's not overpowered at all. Advanced tactics exist as a Pyro too. Exhibit A:
http://www.youtube.com/watch?v=ndZoP4yctqA
Demomen are the most powerful class in the game yet everyone bitches about Pyros. D:
As for the Heavy, he relies on situational awareness and intelligent gameplay more then anything. A good Heavy is someone that knows when to be spun up, when to be using the Shotgun, when to be holding point and when to be pushing forward. A good Heavy is someone who can also quickly prioritize targets. I main Heavy and have logged more hours on that class then any other class, my second being Soldier.
The Heavy is in a tough spot right now though. He get's trivialized by good Demomen, Soldiers, and Pyros. Luckily Valve is buffing him soon, I confirmed it with an email to project lead Robin Walker.
If you want to talk overpowered, The Sandman and FAN are absolutely overpowered. Give the most mobile class in the game a ranged stun and a gun with knockback? WTF?
Getting high level unlockables is a bug that Valve is going to patch out. They were supposed to patch it out awhile ago, but I guess it's low priority since it doesn't affect gameplay at all. It's basically a bug in a weapon unlock system that Valve may be implementing in the future, where you can find higher level basic weapons, for example a Level 10 Flamethrower might grant you 10% extra damage, and a Level 5 Shovel might give you 10% extra health. This is all hypothetical though. The bonuses will always be small and never game breaking.
Al says the same thing about the whole game "I'm not reinstalling it because I suck!" Well you're not going to learn if you don't play! 
