Wirelessly posted (iPhone: Mozilla/5.0 (iPhone; U; CPU iPhone OS 2_2 like Mac OS X; en-us) AppleWebKit/525.18.1 (KHTML, like Gecko) Version/3.1.1 Mobile/5G77 Safari/525.20)
I kept mine on.
I type pretty fast on my phone, so auto correct comes in handy.
It's not 100% accurate all the time, but it's a nice helper.