This is just what we needed to manage our bilingual Joomla site. It lets us handle the translations straight in the CMS, and the language selection module lets users pick the language to use.
Installation was a breeze, with two small exceptions. Fist, "ISO language codes" can be either two or three letters. It seems the one we were supposed to enter is "se" - which is neither of them, but the two-letter country code. (For Sweden, not for Swedish...) No biggie. The other thing is it took me 20 minutes to realize I was actually already done with the installation - on the Components > Joom!Fish > Translation screen you have to select something in the "content elements" dropdown or it looks as though there is nothing you can translate. Pretty obvious when you know it although I would have used "all" as default rather than "none".
All in all - this really works. I'm happy.