Demystifier said:
By incomplete, I mean an effective theory which describes only what we, the human beings with limited abilities, can observe in practice with current technology.
That's of course a hard to answer question. We can always only get information about nature by observing her. It may well be that we cannot observe some aspects of nature. Also any theory is always "complete" as long as no observations indicate that something is missing. For me to say "a theory is complete" always includes an "as far as we know now", and in this sense many previous theories turned out to be incomplete in the one or the other way.
In that sense, as far as we know, QT is complete. It precisely describe what we observe. The key issue we always come back to in our debates over interpretation is the probabilistic meaning of the state. According to QT the implied randomness of nature is fundamental, i.e., it is not due to lack of knowledge about the value of an observable but even if we have determined the state of a system completely, i.e., determined the values of a complete set of compatible observables, some other observables are indetermined. According to QT this indeterminism is not due to lack of knowledge of the state but it's a necessary conclusion of the theory.
So far, despite some effort, nobody has found a way to save the determinism of classical physics in a way that's compatible with the observations. E.g., the time at which a given unstable nucleus decays is indetermined. It's not due to a lack of knowledge about its state but it simply is indetermined.
Everything we can say about nature is however only preliminary in the sense that we can always only use or most up-to-date knowledge (condensed to theories) to make statements like these discussed above. Maybe one day somebody finds a deterministic theory, but then it must explain at least the same phenomenology as QT does, and I'm not sure whether those who feel uneasy with QT, particularly it's state on ontolgy, will feel more comfortable with a non-local deterministic more comprehensive theory. If there's "quantum weirdness" (which I don't think there is, because I accept the posibility of genuine randomness without any quibbles), then I predict there'll be even weirder ideas necessary to formulate such a non-local determinstic theory.