We actually had someone say that the new version is so much better than the old book, even though it's incomplete, that it's like a medical trial where the treatment is going so well it'd be unethical to keep people on the placebo. A bit hyperbolic, yes, but so is "this doesn't help anybody".
Although I have some years of practice in programming, I always prefer to learn new languages using some kind of practical tutorial that introduces the topics as we go along. I've just finished the guessing_game tutorial and really understood the general idea of cargo, externs, associated functions, etc.
Congratulations, and I hope that the rest of the book is as practical on introducing the following concepts as the tutorial was for me..
They're example driven, but most aren't as large as the Guessing Game is for the most part; the I/O project chapter is, and we'll probably have one more near the end of the book as well.
I found the new version significantly better than the old. I immediately 'got it' after reading some of the new chapters compared to the more complete old version which I sometimes struggled with for a while.
I would definitely recommend this to rust beginners, and tell them to just use the old book where the new isn't complete.
14 out of 20 chapters have at least a draft, so this is still useful, even if it's not complete. I generally tell people to start here and then go read the old book afterwards to get the stuff that's not there yet, if they have the energy.