Guns of the South was a wonderful book. The one detail that really made the entire book for me was how the South, and later the North, reverse-engineered the AK-47. I know thats a small detail but too much time-travel fiction has the people of the past getting all googly-eyed at the technology of the future, and in this book people acted the way people would: shock at first and then quickly adapting.
This book, despite the initially silly deus ex machina, also has the best treatment of the historical figures and what a victorious South would look like. Turtledove's later books haven't even come close to this effort.
The pen: it's not just for drawing any more.
I'm not knowledgeable enough to give an opinion on the veracity of any of that, but it does make me want more sci-fi exploring this possibility, not in a fluffy Matrix-y way, but rather extrapolated from current scientific discoveries and trends.
Thinking of a world where the current science has proved to a very high degree that the world is probably simulated and this knowledge has become mainstream. How this would affect further research, how it would affect society, religion, or even daily life. People finding ways to 'hack' the simulation, finding ways to try to communicate with whoever/whatever is running it. People who feel liberated by this discovery and the people who completely lose hope because they feel like their lives aren't "real" enough any more.
The problem with Terminator / Star Trek and even Doctor Who is the writers try to shoehorn a non-linear means of travel into a purely linear narrative.
For example, I just finished watching the 2005 Series 1 of Dr. Who for the first time. In the finale, the Doctor remarks "No one can save us. I'm the last of the Time Lords. None of them are left to come here." This statement was so ridiculous in the context, it took me completely out of the story. Sure, the Time Lords were exterminated in year X, but a time lord from year X-1 or earlier could have popped into her Tardis and come forward to save the Doctor in year Y. A time travelling race would essentially be immortal. Sure they would all die on date X, but they would continue to exist in dates of X.
And with the Terminator movies, I don't understand why there isn't a cascade effect. When your efforts fail to kill Linda Hamilton in 1984 or 1991, why not go further back. Find Linda's mother and kill her while she's pregnant. Of course, a resistance agent will show up and try to stop this. So the robot has to go further back and kill the grandmother, which leads to another resistance agent following. And so on, until I can see a robot going to a point millions of years into the past, trying to squish the first creature emerging from the ocean to walk on dry land and an agent showing up with high explosives to stop the squishing.
Sorry for the rant but writers who won't think through the implications of time travel are always a great annoyance.
It's just as well. I grew up with TOS in reruns and loved it. Liked some of TNG and DS9. But it really should just die. There's no point to it anymore.