I loved this story, it was a great alternate world which can be called the DC Universe's version of Marvel's Age of Apocalypse, showing characters we know having gone down different paths, never came to be, or replaced all together. The real show stealer is this reality's Batman who is this timeline is Thomas Wayne, a completely new approach to the vigilante, more brutal, kills, and makes doctor quips. I want to see more of this Batman, perhaps a comic series detailing his adventures becoming Batman, and his battles with that reality's Joker before meeting The Flash. Another stand out character was Captain Thunder, a new take on Captain Marvel/Shazam, instead of just Billy Baston becoming The World's Mightiest Mortal, it was now he, Mary Baston, Freddy Freeman, and three other children that had to speak The Wizard's name and merged together to form The Big Red Cheese, which I think is an awesome update to the character and one I wish DC would of continued with in their rebooted Shazam who in place of getting his powers from the six Greek legends now just got his abilities transferred to him from the dying Wizard.
The only real negative I have is this story feels incomplete and rushed being only 5 issues, DC has done this before with Blackest Night and Final Crisis, making one-shots and mini-series of major plot elements that should been in the main event book. I feel Flashpoint could of been a far greater blockbuster "Crisis" if the points of views and exploits of other characters like Aquaman, Wonder Woman, Abin Sur, and Hal Jordan were there beside the adventure of Barry, those additional pages and issues could of raised the bar and placed it on par with other DC must-read epics. I do have to wonder though if Geoff Johns originally came up with this reality changing story for his run on The Flash's main book or just a cool mini-series idea before it was adapted into the cause of erasing the previous DC Universe's continuity and merging it with the Vertigo and Wildstorm universes to form the rebooted New 52 universe, because to me it really feels tacked on to the end there just to give a in-universe explanation for all new #1's, and altered origins.