Dynamically updating the Text.text property especially if it's done every frame (for example when trying to crate a 'typewriter' effect on a large text) has potential of creating a lot of garbage, since a new string is discarded every frame. This might have a noticeable impact on performance, especially on mobile devices.

It would be nice (if that is technically viable) if Text used a mutable type to store text internally, and exposed a StringBuilder or some IEnumerable<char> type so that text could be changed without having the gc remove any discarded strings.