I really like how in character they are. You can see it in the little things, like Rin still being asleep even when everyone else is up, Saber's cool non-reaction to Illya teasing about boys lusting after her, Rider's muted reactions except when Sakura is involved. And I can even see the games premise happening in cannon, their reactions being just a little off. Saber shoulders a hard responsibility (in her view), Illya's malicious suggestion of torture instead of killing, Taiga's confused panic and the others. There is still some OOC actions but it's mostly fateful to the originals. The only one who is OOC would be Shirou and that might be because we haven't seen much of him yet.
Regardless, I am really looking forward to how this continues. Great so far.