I've been an enthusiast of language learning (and teaching) for almost a decade. Memrise has an absolutely beautiful interface, and I love its responsiveness and colorfulness.
That said, you're doing yourself a serious disservice if you're using it for learning Mandarin. Aside from the considerable disadvantage of any language learning effort that focuses on single word flash cards to the exclusion of sentences, it propagates some misunderstandings specific to Mandarin. The most serious problem is that it treats single characters as "words", despite the fact that the vast majority of modern Chinese is disyllabic. The word for child is 孩子, not 子, which is found in hundreds of words that have nothing to do with children. Similarly used in isolation, 土 is as likely to mean provincial as it is to mean "earth" as taught in the series.
If you really want to learn, you'd be much better served by one of the services that gives you access to lots of audio, as well as flashcards done well. Try popupchinese or chinesepod. I really recommend the China Breeze series of graded readers, too.
That said, you're doing yourself a serious disservice if you're using it for learning Mandarin. Aside from the considerable disadvantage of any language learning effort that focuses on single word flash cards to the exclusion of sentences, it propagates some misunderstandings specific to Mandarin. The most serious problem is that it treats single characters as "words", despite the fact that the vast majority of modern Chinese is disyllabic. The word for child is 孩子, not 子, which is found in hundreds of words that have nothing to do with children. Similarly used in isolation, 土 is as likely to mean provincial as it is to mean "earth" as taught in the series.
If you really want to learn, you'd be much better served by one of the services that gives you access to lots of audio, as well as flashcards done well. Try popupchinese or chinesepod. I really recommend the China Breeze series of graded readers, too.