This is a rant. You've been warned.
1. We are sloooooowly introduced to either (mainstream) a small cast of characters or (genre, epic fantasy in particular) an extremely large cast of characters. In the case of the small cast, each character will be imbued with some sort of character flaw that repulses me. In the case of the large cast, none will be obviously "the main character."
(this girl is too happy, she must be reading a Middle-Grade/YA book...)
2. In genre, a ponderous prologue will introduce me to events that make no sense whatsoever even after I've read 6 chapters, which is about 283 pages into the novel with another six hundred left to read.
3. In mainstream, the repulsive characters will moan about their life station, while bad things happen to them and/or their repulsive natures cause bad things to happen to them.
4. four hundred more pages will transpire, during which a total of three action sequences are shown, and possibly as many as a dozen new characters are introduced. Nothing else happens.
5. A month will pass. I will find that I procrastinate reading "my book" for enjoyment because there's just no joy left in life.
6. Around page 800 I'll just start skimming (I don't skim fiction, it offends my fiction sensibilities.)
7. Within fifty pages of the end of the book, every single character that didn't repulse me will end up dead in some manner or another, usually gory.
8. I will finish the book and find myself slumped into a deep depression that lasts weeks and weeks...
I pick up a YA or Middle-Grade book, finish it in 3-6 days, and all is right with the world. The sun comes out, the girl gets the guy, the bad guys are vanquished, at least for this book, and there are reasons for living yet again.