I've read several of his books. Overall, he's knowledgeable. Still, you have to take artists conceptions with a big grain of salt. Remember the F-19?. That model was based on mid-1980s speculation of what a stealth fighter would look like. Remember everyone's surprise when the F-117A was unveiled? It didn't look anything like what everyone expected.

While the Stealth Fighter was a highly classified project at the time, there was a lot of discussion about it dating from the September 1980 issue of Armed Forces Journal that discussed Lockheed's Have Blue project in general terms (AFJ found out about stealth but didn't publish it until after Jimmy Carter revealed it while running unsuccessfully for reelection in 1980). There were 3 F-117A crashes during the 1980s. In the best lead in sentence to a magazine article that I've ever read, Time or Newsweek wrote "If a plane that doesn't exist crashes in the forest, does it make a sound? Not if the Air Force can help it."

Reconnaissance satellites provide virtually complete coverage of the Earth's surface over a period of time, but they are only able to image a specific point on the Earth for at most a few minutes a day. They also have the disadvantage of being predictable when they're in range, so the enemy knows when to hide what they're doing. You can maneuver the satellite to change when it'll pass over the target, but since these satellites have only a limited amount of propellant, maneuvers are a very big deal.

Super speed reconnaissance planes like the Blackbird and their crews took many hours to prepare for a mission. You don't just scramble them quickly like you do with an interceptor. As fast as they were, they still took time to reach their destination. The Blackbird was also expensive as hell to operate and required a fleet of special tanker planes filled with a unique fuel (JP-7). It was killed during the time when General Welch was the Air Force Chief of Staff. At the time, he was quoted as saying, "If it doesn't drop bombs , we don't want it." He wanted the Blackbird funds for combat aircraft. IMO, Welch was an ass.