For not having tested all the long list of plugins available in the official directory of extensions for Wordpress, I shall give you to give me your opinion on the plugins Multi-language and that you are including more fun to use.

For my part, I am based for the first download on those who had the maximum download and a recent update compatible with version 2.9.1 of our favorite tool for creating and managing site: Wordpress!

No url translated into the language with qtranslate is one of the big black dots that are the permalinks in your language.

Another article of inspiration for multi language plugins.
http://www.webgiraffe.net/2010/01/14/multilingual-seo-wpml-vs-qtranslate/