How to use it?.. How to use it?! Use your imagination! The possibilties indeed are amazing!
1. Retreating, this is amazing stuff when you're running away from a soldier or someone else.
2. Controlling, use this to push people down from a ledge, or to push them to a bad position (in front of a turret, or in front of your teammates' line of fire for example.) - this also messes up their aim most of the time.
3. Pure wtfpwnage, it feels amazing when you can predict the timing of when the enemy soldier is going to shoot his rocket in a close-combat fight.

*BOOM* Dodge this!
4. Übercharge nullification, you can either block the übered one, or push his medic away from him --> byebye über.
5. Stickyfields, you can indeed push enemy sticky fields away.
6. Sentry Guarding, you can protect a friendly sentry from projectiles by reflecting them back while the engy repairs them.
7. Grenades, even if a grenade is not flying, you can convert it to a friendly one by air compressing at it. This makes your teammates immune to it.
8. If you use this to an übered enemy that is standing in front of your SG (for example: überheavy with his minigun rolled), the SG will push the poor one away.
.. And so on. Just use your brains! I'm so in love with pyro right now due to this. <3 Only thing that sucks about this update is the backburner and it's +50HP.