I too read Schnell's book about 5 years ago. When my parents were studying in 1971/72 "Thirty Years" was THE apostate book everyone was warned about in loud whispers. So of course when I decided that I was done with the WTS, I added it to my reading list.
Does Schnell whine? Yeah, he does. Would I recommend as a "you need to read this to figure stuff out and heal book" (like Ray's)? No. But I thought that the insights Schnell had on the org. during the Rutherford years in Europe were quite interesting. A viewpoint not really found in Ray's works or Jim Penton's.
RN