My feelings on the subject? Well this may be a bit long. On the 2/2/2 dynamic being broken I have this to offer... now we have a 3/3 dynamic, three fliers and three ground ponies.
It has officially been said that twilight will not leave her friends or outlive them, which I feel should be stated first since these are peoples biggest worries.
Lauren Faust had always intended for Twilight to be Celestia's heir (though she later clarification not a princess, which I question because what is the heir to royalty but a royal-to-be?).
Twilight has not become some goddess among ponies, nor is there any reason to believe she will be anymore powerful then she already is.
Hasbro gave the writers a difficult task, to make Twilight an alicorn in a single episode... based on what I have seen M.A. Larson did a good job of making it work as best as possible.
Yes there is a problem of pacing, yes they could have explained it better, yes they could have hinted of her change in other episodes better.
Not everything Hasbro has done is good, not every episode is as good as others. The very idea of Discord being reformed is laughable to me and makes as much sense as the Joker being reformed. Which is why I believe Discord is only bidding his time, waiting to see what will happen, having manipulated the Mane Six in allowing him freedom on 'good behavior'.
Would I prefer Twilight to be a unicorn? Yes but I have come to terms with this change and have even considered the many possible episodes they can make.
Characters change, this is a fact a life, at least if your willing to allow change and development to happen. Only a fool would try to keep things the same, as it is through change that new ideas and stories can be made.