I like how easy it was to use, as well as all its features! The interface couldn't be any simpler if you're looking for something with no frills but very effective at what they do - translating documents into other languages (or vice versa).
You have your choice between free accounts which are limited in terms of number/size limitations per month; paid plans where there's more flexibility over usage limits etc., so this could depend greatly upon whether those particular services suit your needs best. We've been using them since we started our business about 4 years ago now, when most companies had little knowledge regarding cloud solutions such as these ones available today online nowadays.