This is definitely one of the jewels in the Flashpoint world. Deadman & the Flying Graysons gives you a good understanding of the dynamics between the Graysons and how other DC characters evolve with their special training.
The Flashpoint series gives us a new way to look at cherished DC characters that have populated out cultural awareness and are given new life in a new context (world). Flashpoint fits nicely with the other Elseworlds that populate the DC Universe/Multiverse.