One of our readers pointed out that we did not mention how easy BlackBerry 10 makes switching between languages or even typing in multiple languages. You can have up to three languages enabled at a time from the 33 supported languages on BlackBerry 10. BlackBerry even added a mode that lets you type in all three languages and it will automatically recognize which one you are writing and provide relevant suggestions.
They also make it easy to switch between languages by holding down the second key on the bottom left with a globe on it. You then swipe your finger up to the language keyboard you wish to switch to. I use it to switch between Hebrew and English which is really nice though I want them to add a toggle option by hitting that key twice.
To add languages or change the options just go to the settings and select language and input. In there you can add languages or change the options.