Extremely slow, inefficient, buggy and inconvenient.
The app is horrible. Developers have not used any of the standard elements of iOS, trying to make it “nicer”. But they only make it really inconvenient. The worst is the input of the text. It is not a native iOS input. Which means, that you can not use the translation tool in the popup (!) Often the keyboard is not shown. The typing is laggy, which results in a lot of typos. When you open a conversation, it is also a non-native element, you could not select the text and copy it. You could not use iOS translation of the selection. You can not use iOS “Look Up” functionality. It is only possible to use the app’s copy and build-in translator. The icons are non-intuitive.