In my opinion, version 2's documentation is superb. I can't compare it directly against version 1's (never used / read version 1), but it's well written, well structured, has clear examples (including some which are non-trivial), and dives into various concepts (e.g. the section on HTTP caching). Overall, excellent documentation.

Here's a link to the documentation if anyone's interested: http://symfony.com/doc/current/book/index.html