I was conflicted the first time I read this. I wanted to love it, but didn't.
The 1st issue is we didn't learn anything about the Wonder Engines, so the whole underlying plot was unfulfilling. The 2nd problem is I didn't believe all Galen & Piper's actions. Galen not telling Piper about his sleep issues? No. And the resolution to their relationship problems? I felt offended on Piper's behalf.
Which is too bad, because LIKE Piper & Galen