As far as I'm aware, this is the 2nd TV adaptation. The first was on the BBC and starred Stephen Mangan. Neither follow the source material to any great degree. Adams had no role in either. 95 percent sure he was already dead by the time they started making the BBC adaptation, and this one's newer than that one.
The BBC one was pretty good, so I'm willing to give this one a shot. Departing from the source material isn't a bad thing in and of itself, just look at Blade Runner
In related news, I think I remember hearing that the BBC are doing another adaptation sometime soon?