I thought there was a trial period as well, but the hotspot errored out, and turning it on required a phone call to CS and and I got an explicit CS statement to me that 1) there is no trial and 2) it's $29 a month and yes you can turn it on and off.
I was staying at a hotel charging $15 a day for internet so it was cost effective to turn it on, I saved $45 over the course of my stay over paying the hotel.
Haven't tried to root, but prefer free to $29.