I loved how much it emphasized the fact that no one is either all good or all bad; rather, all the characters lay in varying levels of the gray area. Even the most virtuous characters have their moments of questionable decisions and moral ambiguity. Despite this, it's easy to tell which characters are bad news. Dostoevsky's characters are incredible nuanced. Each of the icky characters is icky in his own unique way, and the reality of their ickiness makes you cringe.
The entire host of characters is varied, human, and rigorously alive. Dostoevsky manages to dig deep into each character's soul, sometimes bypassing such trivial things as physical description, and brings the character's true motives into the light in very few words.
And then we come to the plot. The story is heavily introspective. Every plot point that occurs has something to do with the mental, emotional, or spiritual state of those involved. Moments of discovery, redemption, or tribulation are shown mainly through the thoughts of the characters. I expected to get tired of this, but I didn't. Nowadays everyone tells writers to "show, don't tell," but look at what Dostoevsky has crafted by putting action secondary to character development. It is one of those few stories in which the plot is driven by the character development, rather than driving the character development.
Dostoevsky doesn't gloss over things. His descriptions are blunt, straightforward, and sometimes brutal. He makes you feel what the character is feeling, often down to physical sensations. The mood of each scene is revealed in the way it makes the reader feel, as much as in the way it makes the characters feel.
I didn't really like the epilogue, but that's personal preference. I wanted to read more!
If you're looking for a book that challenges your intellect through the lens of vivacious characters, an impelling plot, and wonderful writing, read Crime and Punishment.
(Oh, and if it sounds a bit somber for you, I promise there are funny parts!)