In addition to version control, another nice thing about LaTeX is the ability to leave comments in your document, just like in any other program. Comments like "this paragraph makes no sense, be sure to clarify it before sending to the editor", for example. Or point-form lists of what you want to get through in each section. It's a very handy programming tool to have access to when writing a large document. And just like when programming, the comments don't show up in the final "compiled" product.

There may be better tools out there if you have a big budget, but I'd have to agree. I got sick of word and its quirks when writing my thesis (sort of a technical book if you want to think of it like that). Emacs and LaTeX were a life-saving combination. Bibtex took some getting used to for the indexing, but that was the hardest thing to learn.

Formatting is easy. Large projects are easy. It copes with all the major image formats. And if using a text editor is not your thing, there are pseudo-wysiwyg gui's available.

On a side note, there are also (problematic) tools to convert your document to html and many other formats once you have it in tex.