New Scattergun is just another case of an unlock that would've been perfect to balance Pyro, but went to a class that didn't need it instead. :< Would've fixed both his mobility and range issues.
Pistol looks swag, but that's about it. SMG was already the weakest gun in the game, reducing clip size and lowering firing rate for a 3 second crit boost in a situation where you probably aren't even going to benefit from it does nothing for you. New rifle has less bodyshot damage for an upside that isn't always active and will almost never make a difference. The bazooka description's pretty vague but it sounds like it'd lose to anything in a direct fight or even ambush, and is probably just major reflect fodder.
And then that flare gun.
15 damage flares yeahhhhhh
I'd have to see the knockback and AoE size though, but knowing Valve it's probably direct hit AoE with really minor knockback.