As far as it being a masterpiece of engineering...well, it has a LOT more moving parts than other carbs of its era, that's for sure! So if more parts make it a masterpiece, then perhaps it is!
What the Qjet did with it's nest of metering rods, etc, was an attempt to fine tune the mixture FOR EMISSIONS PURPOSES throughout the range of throttle opening. You have to remember again, that this was a carb SPECIFICALLY designed to meet ever-tightening emissions requirements when engines were not electronically controlled in any way. So the stepped metering rods were there to keep the metering adjusted to the leanest fuel delivery possible that would keep the engine running. Once at WOT, all the rods are clear and they have no effect on the mixture.
Of course, this lean setting that was good for emissions was not so good for midrange operation and led to complaints among the performance crowd about poor off-idle performance and general midrange operation though most folks in 4 door Oldsmobiles/whatever didn't really notice or care. SO...performance oriented owners changed the metering rods to aftermarket ones that would allegedly "correct" the problem. But often, as is frequently the case, owners figured if richening a little was good, richening a LOT was much better! So sometimes they are running very rich, especially when combined with floats that don't and leaky casting plugs. Folks also commonly changed the air valve adjustment so that the secondaries would open earlier - usually much too early - putting a huge "hole" in the power curve though giving the "feel" of "WOW" when the engine finally got enough RPM to actually use the airflow and "kicked it.". It felt "wow" but the car went substantially slower on the track.
But again, the most important thing to remember about it is that it was a first generation EMISSIONS carburetor; that was its reason for being. The fact that it also came on GM performance cars was due to emissions, not due to GM's performance divisions wanting to use it. And, like many "first generation" emissions items, like Cat converters, airpumps, etc it met the Fed emissions requirements with the sacrifice of some driveability.
Marine Q jets have (at least they are SUPPOSED to have) different metering rods than automotive Qjets to provide a richer low/mid fuel mixture - this was essentially what the performance folks did with their car carbs though, of course, it was "illegal."
As I said before, they can be just fine but they do take some fiddling. It's not complex in the sense that "normal" folks can't work on them but someone who is not familiar with the quirks, "fixes" and the frequently-changed metering rods and who just slaps a NAPA "rebuild kit" in one may be quite disappointed if the stars didn't align (no leaking casting plugs, no non-floating floats, no wrong metering rods, etc)
