I haven't played cold steel series yet - but coming from the Trails in the Sky 1 to 3 - I could definitely tell it felt a bit more modern, especially the Steam version. Looking forward playing Azure.
I'm honestly not big fan of the quartz system and level cap though. It's so open, but feels pretty limiting at the same time. Good thing is it's got more manageable size of characters, so I don't have to swap characters too many of times like FC/SC/TC - that sometimes I felt like what's this low level character doing in my party, and felt like I had to level them up to my main characters. (which took long time) - Zero was much more manageable in general - as you are stuck with your set team members in most cases, except a few times.
However I like the faster battle pace and all.... but for me, the best part is that campy, anime/manga like storytelling that encompasses the whole world building so far.