As many others have already mentioned, there are a lot of fakes and scammers here. Several times, I encountered women from various countries who eventually asked me for money.
Ghosting seems to be the norm here. I have never seen it so prevalent on any other app. Even if you have an engaging conversation, often for weeks, the likelihood is quite high that the person, especially female members, suddenly stops responding out of nowhere.
Building real communication sometimes feels almost impossible. With many female members, it feels like you’re having a monologue. It becomes especially absurd when these people state in their profile that they want more than small talk or that messages like "Hi, how are you?" will be ignored, yet they themselves contribute nothing to a deeper conversation. I also find this complaint quite ridiculous. Sure, small talk shouldn’t be the norm, but you have to start the conversation somehow, and for the beginning, it’s not wrong. Often, such users have very empty profiles, so even if you want to avoid small talk, there's no background information to write something original.
Many seem to confuse this with a dating app. I’ve even seen some female members listing in the field "My perfect tandem partner should be..." qualities like "tall" or "handsome."
Other issues that I’ve noticed or that bother me: Users often give false information about their language proficiency. Someone might claim to be fluent or even native in English but then make mistakes in the simplest sentences. If you start correcting all the mistakes in messages, many users quickly become discouraged, even those who are in general good and it just it's minor mistakes you correct. The result is, once again, classic ghosting.
The support here is terrible and seems very arbitrary.