There are some good points in this thread and there are some bad ones. A lot can be said about the addition of the QF buffs, but as someone who is using it a lot, here are my opinions and observations thus far.
First, I'll agree with everyone who commented about how ESEA changed their policy regarding huge weapon changes mid-season. It definitely would have been banned in seasons past after having huge stat changes. So would the winger, etc. But it wasn't banned. Instead of complaining about the policy change, we decided to give it a try and see if it's viable.
What we've discovered is that it certainly *can* be viable in most situations, but it requires substantial forethought and planning, as well as utilizing the additional mobility to escape unfavorable situations.
It's infinitely more fun to play medic, and definitely increases the necessity for team cohesion. Your pocket can't just randomly rocket jump without coordinating it with you. You must coordinate jumps in so you're not accidentally hitting an opposite key which causes you to fly straight up, etc. Your team isn't as buffed so they need to get rebuffed much more often and you have to focus more on keeping them out of red because they need to be able to stay in the fight longer, or the faster heal rate is useless. All these things and more make it more interesting, challenging, and just more fun to use.
Some would argue that it makes medic easier because you don't have to focus as much on uber advantages/disadvantages. To a degree, this is true. You know that if you spawn at the same time or earlier than the enemy medic, that you definitely will have an advantage of some sort. On the flip side, it's so much more important to push before the enemy has uber that I would suggest keeping track of percentages is just as important as before. The Kritzkrieg tactic of "kritz into them, make them pop, and back out" doesn't work quite as well with QF since you have to fully commit your pocket -and- medic just to get the force, and then the demo very likely has you trapped by the time your charge wears off, so you need to have creative escape routes that frequently need to be invented on the fly, and coordinated between the pocket and the medic to keep you both on the same page. Nothing about this weapon seems overpowered--just different.
A lot of you are commenting about how it's silly that you can cap while using the QF charge. You can cap with Kritzkrieg. You can cap with Vaccinator. Why should quick fix be any different from those? Putting your medic on the point, in most cases, is going to be a death trap for him even if he's using the QF charge. In a case where the medic and pocket can get to the point to cap before you can deal 189 damage to the medic and stop the point, you probably would have lost to a scout capping anyway.
There's much to be learned about it in practical use, but none of it seems game-breaking.