This is easily the best French dictionary app. A lot of care was put into making the interface clean and intuitive. And the content comes from LeRobert- arguably the most authoritative source possible for the French language.
The only issue is that its clumsy to close definitions. You open a definition by tapping on the word, but to close you have to click on a little "arrows" button on the other side of the screen. The definitions also stay open forever, so after awhile a bunch of definitions are open. Id expect them to be closed automatically at some point, like when you open the app.
YesNoCancel about Collins-Robert Concise, v2.4.2