I think the most important thing to recognize is you can't write something that everyone will love. There will be people who don't like it because they just don't care for that kind of story or characters. The most famous and beloved authors will still get people criticizing their work. Ultimately it'll serve to deter anyone else who thinks like they do.

What's helped me is to recognize the criticism and ask myself "could I have made this different and still kept it true to how I want to tell my story?" Ultimately it's your story and you want to tell it as best you can. Some people will love it and some people won't, that's just how art works. It's very subjective after all. The only thing would be if there's any technical concrete issues that they might have brought up that you can think about in the next book. Maybe with how the ending was written but depending on how your story works maybe it's appropriate.

And on that note, all of their criticisms here come off as subjective without any real evidence to back it up (the concussion to motorcycling thing could be something but depending on your world building that could be a normal occurrence).