Hawke - I understand that main-protagonist cameos are not easy to write...and it's impossible to have such a cameo without angering some people. Everyone played out their Hawke's differently, and everyone has a different idea of where life took her/him after the events of DA2. But that blood magic obsession for example was simply weird and rather unnecessary, imo. I liked my "canon" Hawke in DA2, but DA:I Hawke annoyed me.
Varric - I still like him and he had some good scenes (especially with Cassandra)...but he was simply more awesome in his homeland compared to his DAI counterpart. Varric has great chemistry with Hawke, but I can't say the same about Varric and the inquisitor.
The major novel characters (basically all of them) - They were either completely sidelined (Adrian, Rhys, Evangeline) or not developed at all in DAI (Fiona, Briala, Celene). I mean, I still enjoyed Wicked Eyes and Wicked Hearts for example...and I'm quite happy that I can get Celene and Briala back together again. But the only reason I care is because I've read TMA.