The main nod to continuity is that Gwen pops up but is in the US after Miracle Day and in fact more importantly is this is also set after Children of Earth and it is the destruction of the Torchwood Hub that caused an egg-shaped alien artefact to be blown into the Cardiff sky and land in the allotment shed of young Yasmin. What you are asking now is was it any good?
We actually have a fairly standard Torchwood tale of aliens and artefacts set in both Wales and London but now centring on Sgt Andy Davidson (which is useful as this is read by Tom Price who plays the part). Andy is on his own to deal with Yasmin, her supposedly dead brother and a alien intent on capturing a device that would (for a change) mean the end of life on Earth.
The tale proceeds at a good pace, we end up not missing Gwen or Jack but instead get a resolution that fits Andy’s character well – he is somewhat dragged along by events but has principles he won’t compromise. There is action, some exploration of the relationship between Andy and Yasmin and we are still in what I would call a recognisably Torchwood universe though as we now have Andy as the lead character (and to be fair Rhys has been before) the definition of Torchwood is now getting rather stretched.
The author and the reader
The story is written by David Llewellyn who was written other Torchwood and Doctor Who novels and clearly has a knack for the milieu.
Tom Price does a good job reading it, it is a decent tale and usefully passed the time whilst I was driving somewhere and that really ticks most of the boxes it needs to!