I'm developing an iOS app and I'm not sure if some of the things I've done will be approved by Apple. Sometimes the reasons of rejections are very hard to predict and I'd like to know if something is wrong earlier.
Does it make sense to submit an unfinished app to Apple Store with a release date couple months in the future just to get some valuable feedback from Apple? I'm pretty sure they'll reject such an app, because they don't allow beta versions to be submitted to Apple Store. But, will they provide me some valuable feedback, that certain parts of the app or of the implementation need to be changed for the app to be approved when it's finished? Or, will they just reject it because it's not finished and won't provide any feedback about the already implemented parts?
Tricky. In my experience, if they reject it, they'll reject it for the first problem they find. They won't give you a list of reasons. They won't review it thoroughly once they've seen a reason to say no.
So, while I can't see any harm in doing it, there's no guarantee you'll be rejected in a way that gives useful feedback. More likely they'll pick you up on a simple point, and you'll be no wiser.
Plus, bear in mind, the review system isn't wholly consistent. I've had apps accepted by one reviewer, only to be rejected next time because the later reviewer is more thorough. You could have your alpha app accepted, only to see the polished version rejected after months of work.
A better approach might be to discuss the specific rule you might be breaking on the Apple Dev Forum.