If I am sitting at a computer I prefer using the computer keyboard for sms.

I can send sms through web page with phone service provider, but don't have all phone numbers automatically available.

I can send sms through phone using bluetooth, but don't have bluetooth on all my computers and don't have it turned on all the time (battery life).

Cost per message for Send SMS is slightly cheaper than using phone on current prepay plan, so trying it for a year just for the convenience!