The Idiot was the last book of Dostoevsky that I read, while The Brothers Karamazov was the first.  I can certainly see some reasons a person might hate The Idiot, how vain, shallow and selfish the high society crowd the Prince found himself around were and how they treated him.  The ending was agonizing and very disturbing.  I enjoyed it for a very specific reason, and perhaps I am alone in my interpretation, but I think it spoke to the nature of beauty and the struggle between our higher-self, personified by the Prince, and our more base and possessive self, personified in varying degrees by several of the other characters.  The Prince, who described himself as ugly, sickly, awkward and a stranger to everything, seemed to appreciate the beautiful without any desire to possess it, simply experiencing it on its own terms and completely as "other."  The other characters would identify the beautiful in culture, status, romance, power, pleasure etc., and seek to acquire it for their own and in so doing were turned against each other as competitors and rivals.  Over time and by the end of the book, The Prince had finally become compromised and while not fully given over to complete selfishness, nevertheless had resigned to sharing possession of the beautiful, by then a dead corpse, in tragic irony holding in his arms the very lifeless dispossession of beauty.

This complete contradiction of his once simple and beautiful nature led to his descent into an insanity worse than that which he began with, never to recover.

There was a point in the book where Dostoevsky describes a girl (I'm paraphrasing) as "not pretty, not ugly, but pretty-ugly."  This captured for me a lesser appreciated and even lesser articulated degree of beauty, one that many of us have experienced.  A woman who is on the cusp of being "ugly" but also on the cusp of being pretty...it is a powerful thing.  In viewing her and trying to establish for oneself whether or not you find her pretty, noticing attractive features mixed with not-so-attractive ones, the effect, the realization of which will always escape her, ends up putting her at a great advantage over those with a more conventional beauty.  The reason for this is that in the process of trying to make this determination, the woman has become captivating for the man, and all this due to the very traits that she herself believes to be her blemishes or imperfections!  The man wonders if anyone else notices this contradictory yet strangely complementary mystery play in her features, between beauty and imperfection; he wonders if perhaps someone else has appreciated the mystique born from the aesthetical dialectic playing out in her attributes.  We are drawn to beauty, and in beholding this rare kind of beauty, one is compelled to seek out those pleasing features amidst what at first glance only seemed to take away from them, but ultimately results in only enhancing them.  It's an amazing thing to witness, and a great asset to any woman fortunate enough to be blessed this way.  I think The Idiot eventually leads up to this realization, and that this small phrase, "pretty-ugly" really captures a concept that Dostoevsky was hoping his reader would grasp and value.