Not just you, although like LilyBLily, it's usually further on for me - either I get about 1/3 of the way through and realise that the opening is absolutely dreadful and needs to be rewritten or, like my current draft, get about 1/2 through the first rough draft and realise that a major plot line doesn't work and needs to be booted to the next book, leaving me with a huge hole in the story that needs to be filled. Argh! (This is where I am just now - it's horrible.)
The hardest part for me is usually editing - there is always, always, a point in editing when I am completely convinced that the [insert swear word of choice] book is never, ever, going to be finished and I'm going to be stuck in the never-ending hell-loop of editing forever. And then, at some point after that, the worst of it is done, but for some reason my brain makes me go through the pit of despair first. Every time. Gah!