Camilla's ex-husband is invited, apparently, which might seem even odder in a way - considering that neither Charles nor Earl Spencer betrayed/cheated on each other directly.
I'm no fan of the monarchy, and this coronation (the first in my lifetime) just brings it home that, for a 'democratic' country, we can behave breathtakingly and wantonly undemocratically; but I do think that Charles is facing an uphill battle here, which will probably be the mark of his whole reign. If he invites popular celebrities who will be familiar to hoi polloi, in an attempt (however successful) to make it seem a bit more relevant and meaningful to us all, he is criticised; if he only invites a load of dusty old aristocrats that most of us don't have a clue about, he will be criticised again for being elitist and out of touch with the common people.
The Queen was in the very unusual position of coming to the throne very young and thus spending most of her life as the monarch. It seemed quite natural as she grew with the role and had seven decades to make it uniquely her own, as well as only having a few adult years beforehand in which to make bad decisions that people would forever resent her for.
Charles has spent the great majority of his life filling time whilst waiting for the job - during which he has made numerous very unpopular decisions (as would many of us in that timeframe, but the Daily Mail don't care about us). Now he's finally there, he may only have one decade in the role; highly unlikely to be more than two. I can't see him carving out a grand reputation as monarch for himself; I think more likely he will come to be seen in history as just a bit of a caretaker between QE2 and King William V.