So No Time Like The Past at least on the surface sounds a little far fetched, granted it's scifi and Star Trek so some of more outlandish plots can be found in the genre but when done right any story can be sold as being both entertaining and consistent within the franchise. Greg in bringing together James Kirk and Seven Of Nine dallying with the potential for a disaster but by offering up a well worked time travel story with enough mystery, action and depth for the characters he pulled it off and the story never once stayed into the grave yard of cheesiness.
The basic story has Seven along with Voyager tracking an energy signature via local folk lore of a "wizard" who could transport vast distances, tempting certainly but what they find is quite surprising and more so when faced with no option Seven gets herself flung in her distant past and to a place where a certain Starship Enterprise is in orbit conducting a secretive diplomatic meeting the goal of which is to reduce the influence of the Orion syndicate in that region of space. What comes next is a race across the galaxy and the timescape to solve an aeons old mystery while dealing with a Federation Ambassador who as they do causes all sorts of problems and a determined Orion Captain and crew who see Seven as a valuable resource to be sold to any interested parties with resources to spend for access to knowledge from the future.
It was great fun seeing the crew of the original Enterprise having to deal with another time traveller, more so because in our minds we know Seven and we know Kirk and well you know but thankfully that is never an issue and it's the puzzles and adventure that really pays off. I really enjoy getting more of a taste of the worlds visited in the original tv series especially Cheron (Let That Be Your Last Battlefield) and we see the world as it was before it's fall when the civil war was in full flow leading to the tragic events which left it a barren and dead world.
I can highly recommend the novel for fans of the original series, less so for Voyager folk as it seems the love of Seven isn't universal but if you are even considering Trek then Greg has a winner as shown by the books performance on the sales charts when it was released.