This is Kirby's second last issue of THOR (with a fill-in before ths last one), ending an epic where Loki had managed to get rid of Odin and unleashed Surtur upon Asgard. In this issue, Loki flees to Earth, while Balder and Sif go to rescue Odin while Thor and the other warriors of Asgard attempt to defeat Surtur.
A very exciting action based issue, with lots of great scenes of Thor and his army fighting against impossible odds. The ending is a bit of an almost literal deus ex machina, but when you've got a character like Odin that's going to happen.
The story is a page short, as this is from that period when Marvel was running two pages with half page ads. Annoying. Colletta inks the story, but it mostly looks good for Colletta. John Verpoorten inks the cover, which is nicer.