Seems like a reasonable service for those who have no alternative, as you say, 3G mobile option may be better for some, there will be a limited but healthy marketplace for this service.
I remember in the days before ISDN lines and then ADSL were available, I used three different return only satellite services, unfortunately they suffered from bandwidth bandits, who decided that "as the provider advertised unlimited usage" they could download movies 24/7, of course this buggered up the service for everyone else. Shouldn't be a problem these days though.