As Bruiser said, most people move on to a cartomizer system after they're frustrated with the Cartridge/Atty combo.
As far as the flavor and burning, there are a few things that it could be. The most likely of which is this; your atomizer has a wick on it, a very small wick that holds the liquid long enough to vaporize it. It only holds a drop or two, so it doesn't last long. Once it gets dry, the wick will start to scortch. The tell-tale that you're about to hit that point is when you get the no-flavor or low-flavor hits, that's when it's time to refill your cartridge, or drip a few more drips.
It's possible that the cart filler is getting burnt, but not as likely. It's also possible that you're over-drawing the wicking potential of the set-up that you have.
Rule number one, with any
vaping system, is: keep the wick wet. If it's dry, it tastes bad, burns, and does all sorts of unpleasant things.
If you're looking to change systems, I would suggest checking out cartomizers.