For those saying to tighten the spread of the flamethrower, do note that a standing pyro's flames are about as tight as they get in terms of spread, until the tip of the flames. To narrow that, Valve would have to make the boxes themselves smaller, which is an interesting idea. Otherwise, they could reduce or remove the random horizontal velocity changes that each entity has every tick which would be appreciated as well. Edit: (Or what Kav said down below)
Personally, I'd like to have some way to actually see what I'm doing with my weapons, and for others to see that as well.
For example, regardless of how you feel about airblast, a good start would be making its range more clearly defined.
Similarly, it'd be nice to see what I'm doing with my projectile shooter gun, similar to pretty much every other projectile shooter gun. Flame mechanics and movement at further ranges is already pretty interesting IMO since it keeps your momentum. Though perhaps it wouldn't be enough, it'd at least increase the skill ceiling of pyro if one could see where they were shooting.
That said, attaching particles to each of the flame entities and making the client do predictions for each of them might be a bit taxing on performance. I'd like to see Valve test hitscan on the phlog, since it at least looks hitscan-esque.