Fast-paced, lots of action, but thought-provoking enough to keep me reading. I didn't get any of the science, but there's basically only one page of the "explanation" of how the protagonist, Jason, was able to go into the "multiverse." 
 The main idea here is regret about the road not taken. There is a Jason who chose family over distinguished career, and there's an alternate Jason who chose to devote his life to career, sacrificing a future with Daniela. These Jasons collide when the Brilliant Scientist Jason invents a way to steal Family Jason's life.