The way to input text is not only keyboard typing but also other ways, 'Select text', 'Input time automatically', 'Input date automatically' and 'Create URL to Maps'. And you can change by tapping whether text of pieces will be included in message. So you can keep the loss of time by typing text to a minimum. And you can make different messages from one template when you have to edit message in any situation.
You can make pieces as group of recipient. For example, group your family, your friends, member in your office, and so forth. So you can select addresses at once and change addresses with a few taps. Needless to say, you can pick one address out from each group. Line-Writer can send message to SMS or Twitter other than E-mail without making another template. It's convenient even if you use a template for sending messages other than a routine.
You can make a 'model' of piece for the sentence or addresses you often use. For example, greeting, places for a meeting, signature, addresses of your friends, and so forth. This function allows you to make a copy as new piece from the model. And you can make a piece which refers to data of model too. Model of piece can be referred from multiple templates. So you don't need to make same pieces for each template. And you don't need to review all templates too.