Multilingual support and database issues -- how many languages?
So the problem is that each new language is stored as a separate column for each translated field (eg title, body...), so the more fields that are translated and the more new language you add, the sooner you will hit a limit of mysql on how many columns can be set. As for the exact number, it depends as well on the type of content you store, mysql has a longer explanation, but 2 or 3 is what I've tested without reaching that limit:
http://dev.mysql.com/doc/refman/5.7/en/column-count-limit.html

Other than that, works pretty ok, but keep in mind that because the structure of the database is changed, it becomes impossible to revert to a single language version.