There are a number of exaggerations in this classic work. One of the things that make them work is that J. Hector St. John de Crèvecœur is at times supposedly passing on things that others tell him. Another thing that makes them work is that he's telling people what they want to hear, or what they wish were true about America.
Look at Letter II for good examples of both of these. When the farmer is talking about his situation, it is too perfect. Marriage makes him "perfectly reconciled" to his life--not happier, not better, but perfect. The farmer says that the American farmer has "freedom of action, freedom of thoughts." That may feel true, but there was a complex system of laws limiting his actions, as well as the threat of violence. When he travels, he always is always pleased when he comes home--not sometimes, but always. That's too perfect.