From what I can tell, the show is doing great with most people, but some fans have been proclaiming that “it’s not good if you’re a fan of the video games”, but then I see people responding with “I am a huge fallout fan and I love the show”. Also, Tim Cain, the co-creator of fallout, loves the show; he loves the details in the background so much that he sometimes missed the dialogue.
So, from my pov, who has not watched the show or played the games, it seems like some people are throwing out “as a fan of the series…” to validate their opinion.