Just finished reading Earth Unaware (New Prequel set at the time of the first discovery of the formics/buggers).
If you’re a fan of the series, I think you will enjoy. If you have not read the series, do not read it first (not due to spoilers, but simply because it’s not as powerful).
I’m not sure if he’s planning a sequel to the prequel (an in-betweequel?), but there are some definite unresolved questions. Good fast-paced read. Overall it’s a much better addition to the series than the new book in the Bean saga.
tl,dr: Don’t read Shadows in Flight. Do read Earth Unaware.