In general, I think that this is a good series. I'm a fan of the books but I recognize that sometimes changes are made for various reasons in adaptations and there will always be a difference between books and TV are different mediums. My husband (who has never read any of the books) also enjoyed the first season/series.
What I like about this series:
Alfred Molina's portrayal of Inspector Gamache is excellent. He beautifully captures the thoughtfulness, compassion and humanity of the character. Many of the other performances are also very well done especially Tantoo Cardinal.
I liked that they filmed in the eastern townships of Quebec, the architecture of rural Quebec is different than the rest of Canada or the northern USA. I liked that most of the cast and crew were Canadian.
The indigenous story arc of Blue Two-Rivers is unique to the television show (not in the books) and is very well written, well acted and compelling. Apparently the show's director is indigenous and they used indigenous cultural consultants. The care that was taken is evident in the show. Although Isabelle LaCoste is not indigenous in the books, I thought it was a good idea to have her characters as an indigenous character who doesn't know the culture (because she was adopted like many in the "scoop) and as an outsider in the police. For far too long in this country (Canada) the issues surrounding the treatment of indigenous people have been ignored. This arc is integrated very well into the existing stories from the book.
Areas I think could use improvement:
The issue that immediately struck me is the lack of French (there is some but not as much in the books) especially with 2 characters. Jean Guy doesn't speak English (and mistrusts English speakers) Gamache and his wife only speak French to each other. As well, realistically most Surete du Quebec business would be in French (except interviewing English speakers). I was surprised that they had Gamache speak with a standard English Canadian accent (rather than British as he does in the books) although I thought that this was probably because it might confuse people who hadn't read the books.
However, my biggest issue was the episodes often feel rushed because they cover an entire book in 2 parts and add the indigenous storyline. In some cases, I feel they would have worked better as 3 or 4 part stories. The best story in my opinion (which didn't feel rushed) were The Murder Stone parts 1 & 2.
Overall, I would recommend this show. We enjoyed it and look forward to seeing the second season/series.