Yes it is, though as Koz notes, their description of “good” recording is detailed and fairly comprehensive, but not “complete”. They mention “room tone” several times, and it is important, but the “type” of room tone is also important - if it sounds like a bathroom or corridor, then (unless that is appropriate for the book, which usually it is not) you will need to do something about the recording location, such as putting up sound absorbing materials around the space or using a “vocal shield” or “vocal booth”. This is a common problem with home recording.
Some of the technical detail is a little bit “out”, for example:
“There should be exactly 500ms (0.5 seconds) at the head of each file”
The start time of an MP3 file is not “exact” due to limitations of the format - what they mean here is “There should be very close to 500ms (0.5 seconds) at the head of each file”.
Also:
“Your submitted files should measure between -23dB and -18dB RMS”
This specification is incomplete as they do not state the RMS “weighting” or “window size”. In practice the exact definition probably does not matter too much - I assume that they are just trying to give an indication that the recording should be “reasonably” loud without pushing the loudness too much - the compression / limiting steps that they describe are likely to be close enough to the right ball park figure. Comparing your recording with some of their published recordings will immediately show you if your recordings are too loud or too quiet. There are also some plug-ins that can give you an RMS and peak amplitude figure for your recording such as the “Stats” plug-in available here: "Wave Stats" plug-in