As someone said before, it's not a dynamic class, and there's no real challenge involved in being decent at the class. Heavy is probably the most unfun class to not only play against, but to play as because of the lack of skill and overall challenge involved in getting kills.

Whenever I play scout and I take out a soldier/medic combo by myself I feel good because I outplayed the soldier as well as the medic to some extent. When I kill a soldier/medic combo as heavy I feel like it was not because I outplayed them, but because I have 300hp and a gun that is automatic and hits for 200 damage a second in medium range. Same goes for playing any class vs. a heavy, I don't think I get outplayed when a heavy kills me, rather than I just got killed by some big dumb mobile sentry gun with almost 3x my health.

Nothing can outplay a heavy in short range if the heavy sees that class first, I don't really consider the class balanced at all for that reason alone. Heavy shouldn't have all of those dumb unlocks and the spray cone/damage needs to be taken down for it to be more balanced.