This story-arc is like an epilogue of the, let's call it, "Speed-Force" saga, which started back and in "Terminal Velocity" with Wally's discovery of the Speed-Force and Linda starting to get worried about Wally's secrets and powers. It's not as thrilling as the previous sagas but it's a pretty good clousure on the whole thing.
John Fox, a new Flash called from the future appears in the present time as Wally goes from century to century trying to get back to Linda, meanwhile, we discover the reason while John went back in time and why Wally can't return.
The villains are kind of weak here, they are barely in the story, John Fox is a pretty stale character, and there are a few things that feel a little shoehorned or under-developed like an "Anti-racist" message involving aliens, but the point of the story is Wally racing back to Linda, so it's ok.
Overall, is a pretty good read for us Flash fans.