Here are some notes about integration with other contributed modules. This is about configuration and integration with other modules to use Internationalization features, but not about compatibility problems. If you have any issue about compatibility with other modules, please file a feature request on the issue tracker.
The Synchronization module works also for CCK fields.
There's no support (yet) for translating single fields into different languages.
The i18n blocks module is not compatible with Context. It won't break your site but just one of the modules will be able to handle the block selection. Change module weights so the one running later is the one handling the blocks.
AFAIK, the Pathauto module plays nice with Internationalization module. In addition to that, there are some features added into Internationalization module to provide different path templates for nodes depending on language.
Note: this won't work for bulk pathauto operations:
- Add pathauto variables to language-dependent variables in settings file, like:
$conf['i18n_variables'] = array(