I really love the way Memrise helps me to learn the language. But it's hard to use when you don't know English - for example, I helped my friend, who's learning English, to set up an accout, but I have to explain him how to use it.
Do you need any help in translating the interface to other languages? I can help with Russian.
There's another problem, to which I've already pointed out, with the "source language" navigation. After I gave a link to the site in me twitter, I got a reply from a friend who had trouble finding an Enlish course - he didn't notice "source language" menu, just like I myself before. I think it have to be automatically set to "mother tongue", that should be asked for while signing up, not later.