I've always been intimidated by sophisticated interfaces and overly "gaming" platforms where everything glitters but nothing is clear. But on improve your vocabulary app everything is clear: the words are immediately remembered due to repetition in different situations, the simulators do not just check — they explain. I especially liked the section where you need to listen and repeat aloud — I see my progress, it motivates. It looks simple, but it works great. I don't even notice how time passes.