I imagine it will work the same as it does on the iPhone. I use it all the time.
I have dictated whole paragraphs, but I find when I do that, I pause and perhaps say "uh" or stumble over a word as I'm gathering my thoughts, and so I then have to go back and clean up the paragraph (still faster than typing the whole thing).
So, what I do now is dictate a couple of sentences at a time, and that works well for me. Punctuation is easy. You just say:
Punctuation is easy period However comma you may have to practice a bit for some of the more obscure items semicolon for example comma when you want to use all caps in a word period.