The movie, in general, is good and entertaining, but being strict, its plot is totally disappointing.
It's visually stunning, nothing more, nothing less. It lacks an actual message and it has plenty of unnecessary scenes which seem to be there just for the sake of teenager fanservice. It isn't dramatically touching either. Just another pointless interpretation of the already seen body-switching concept.
It's certainly overrated. Sadly, it's a total waste of visual resources. Hadn't it been for its popularity, I would already have forgotten about it.
I'd actually give it a 7.5 out of 10, but I'm rating it a bit lower to compensate for other reviews which depict it as the best anime movie ever.