I like using email for more formal communication as I can organize them better. However, text messaging works great in some ways as sometimes it better not to talk to the person, but you want the person to know you are not ignoring him/her. I find texting comes in handy when I don't have time to call a friend for a long chat, but just to let the person know that I care.
I have email function on my phone, but I rarely use it. I don't want to be chased by emails everywhere I go.