I play Pyro, i tend to be either Pyro, Engineer or Soldier. More recently ive been playing Pyro because ive had lots of success with it. The flame thrower upgrade is nice, but the missing compression blast does become a problem sometimes. XD Has anyone noticed a strange bug where sometimes "flames" seem to go through walls, seems to affect buildings made by engineers mostly. You can stand "under" the floor they are on and destroy them, found out by accident the otherday then had a load of people calling "cheating" and "exploit abuse".
I think Heavys could do with an ammo upgrade, they should double it (as an unlockable). Maybe a "sprint" would be good too, make him able to 'holster' his weapon and move quicker, with the drawback being he needs to re-equip it so its slow to start shooting. Help get him to areas he needs to be. Spys need a quicker cloak/de-cloak...
I look forward to the engineer pack though, i hope they give him some cool upgrades for the sentry (shields? XD). Or a link, between other nearby sentry guns so they lock on to the same target (even if it would be slightly out of range of the other normally).
As a pyro, I tend to spray my team mates with flame quickly to check for spys. Its the best class for doing it IMO, if there is a spy there they burst into flames and everyone can shoot them. Assuming they dont burn to death before then XD