The Wisdom of LiveJournal and Smartphones

I figure it is about time for me to join the world of the smartphone enabled, and before leaping into it, I thought I'd check the collective wisdom:

Given that I am a mac-user and a Verizon customer, are there any good reasons not to go with the default of an iPhone5 and a verizon plan?

( More detailed questions about choices and apps behind cut )

Thanks for your thoughts.