people talk smack about q-jets (aka quadrajunk, lol) because they have had so many hands on them that they blown way out a wack.
So just like a holley when its way off, they can be tricky to get back to where it should be set. and most people just dont understand all of the settings.
Also so often I have seen people get a hold of just any q-jet thinking that they are all they same, not understanding that when they come from the factory they are set up for certin motors. the jets, metering rods, air bleeds, all of that is has to be set for the motor your putting them on.
And last thing is that from the factory they are made to to get mileage and running quality, not for peak performance. But once built right they will get all of the above.
And for those wanting to figure the q-jet out, there is a book on them that will go all into what everything is and does, and how to adjust everything.
Or there are a few companies who will build up the q-jet for YOUR setup. You will spend about as much as you will on a new carb, but you will get better mileage, idle quality, and throttle response and just as must power.