Doesn't push notifications so you won't know if you get a new message. My students say the same, which is really a pity because in the end everyone is quite disappointed with the app. As a teacher, i find it really inefficient, given that you can't reschedule lessons on the phone - if you try you just get an "error occured" message. Lamentable. If preply put a bit more money in developing the app, it could have a very positive effect on the students. Maybe give it a thought?