After I make decision about adding english language support I try to choose right solution. There are two most preferable plugins now:: qTranslate and WPML Multilingual CMS. Other plugins like WP Multilingual, mLanguage or xLanguage either haven’t enough features or totally are broken in last wordpress versions.

Undoubtedly, WPML Multilingual CMS have much more features, but it has turned commercial. So evident choise is qTranslate.

qTranslate gives you abilities to write pages, posts, categories and tags on diffirent languages without data base structure changes. So you’ll have no troubles if you delete this plugin. In addition, it may use special plugin tags for any files localization:

qTranslate have good integrational features as well: it supports by Google XML Sitemaps special version and qTranslate META plugin for meta-tags localization.

Some advises on blog interface localization:

• First of all you should add your language on plugin settings page, set it as default and delet unusable languages. Plugin interface very friendly so it’ll be easy.
• For widget titles localization you should use [:en] tags. E. g. in search widget I write:
  
[:ru]Поиск [:en]Search
• To insert language chooser in any place you should call function below:
  
<?php echo qtrans_generateLanguageSelectCode('image'); ?>
• To insert lanuage choosing in page code you should:
  either use _e function. E. g.:
  
<?php _e('[:ru]Отправить! [:en]Send!'); ?>

  or use force locale detect. E. g.:

  
<?php if(get_locale() == 'ru_RU') { ?>
Отправить!
<?php } else { ?>
Send!
<?php } ?>
• Wrong date-time display correction. If it displays date instead of time or vice versa when you tun on qTranslate it needs to change the_time() function with the_date() or vice versa appropriately at theme templates files. It important to use necessary parameters in calls, e. g.:
  
Опубликовано <?php the_date('d M Y') ?> в <?php the_time('G:i'); ?>
• To fix wrong pages navigation links display you should use force detect local and change
  
<?php next_posts_link('« Previous') ?>
<?php previous_posts_link('Next »') ?>

  with

  
<?php echo(str_replace ('.com', '.com/en', strval(get_next_posts_link('« Previous')))) ?>
<?php echo(str_replace ('.com', '.com/en', strval(get_previous_posts_link('Next »')))) ?>

About drawback. A huge one is incompatibility with SEO plugins like AIOSEO, PSEO. You can try to fix it in part using qTranslate META plugin. However you can’t use SEO plugin in this case. Now I still don’t use qTranslate META for benefit of SEO plugin. There is a blog search localization problem as well. Your current language reset to default on serch results page. Although this problems are discussed on qTranslatesupport forum there are no solutions for now.

Undoubtedly, As of today qTranslate – the best free solutionfor wordpress blog localization. I just localize interface for a while but In near future I’ll loccalize my posts about 3D models converting as well.