What does "Yes, and we haven’t even seen half of it." mean in English for Spanish?

In English for Spanish, "Yes, and we haven’t even seen half of it." means:

Sí, y no hemos visto ni la mitad.

Listen to "Yes, and we haven’t even seen half of it.": (If you have an HTML5 enabled browser, you can listen to the native audio below)

This is a phrase that is used in the GamesForLanguage English for Spanish Language Game in the following scenes:

• English for Spanish 4, Level 2, Scene 3