I found it a bit irritating, but also very interesting.
What irritated:
Much was made of the fate of poor old Fido, trapped in the house, but no mention of farm animals. Cows would explode and everything else die - except sheep I guess. But maybe that would have lead to hard questions about farming practices...
It was very US-centric, despite a few bits about the London Underground & the Thames Barrier. No mention of the gas supply network under our streets which might hasten the destruction of cities a bit, I felt
I was unconvinced that the generators in the Hoover dam would supply power for years; they might keep spinning, but I bet the grid wouldn't take it and the station itself would disconnect
I don't think that the dose rates near Chernobyl were high enough to kill all plant life
. Mammals, OK, in the hot spots.
They kept saying that after 5 years the roads would have become greened right over (with nice graphics) but the city of Pripyat seemed still to be mostly there after 20 years.
</pedant>
What was good was the way that the planet got on with it after we'd gone and, frankly, seemed like a much nicer place with a much brighter future. Food for thought.