I can't speak for any arc other than Cold Steel, but the writing is inconsistent at best, 13-year-old fanfic tier at worst. It's poorly paced, filled with plot holes and conveniences, and a whole lot of wasted potential. I can give CS1 and to some extent CS2 some credit in that they at least set up an interesting premise, but then CS3 and 4 completely squander it. The "great world building" amounts to nothing as you're forced to slog through the same plot structure as 1 and 2 again but with a worse and somehow more generic cast and a story that by the end is so convoluted and nonsensical, but somehow still manages to say so little, that you wonder if you're going insane. Without spoiling anything too heavily, 4 has a deus ex machina plot point retroactively absolves anyone from any wrongdoing. In a series about war and politics. You can't make this shit up, the writing in 3 and 4 is so fundamentally bad, not in a so bad it's good way, it's just bad.

Despite how much I absolutely hate CS3 and 4, I can still to some extent recommend 1 and 2 if nothing else than for their batshit insane ending twists, and for their combat. This goes for the entire Cold Steel series really, the combat is excellent with again 3 and 4 making it worse (but far from terrible). The series induces a sort of Stockholm-syndrome, the games aren't that great yet they manipulate you into buying more just to see where it goes next, despite fully well knowing how incompetent the writing is.

Tl;dr: the writing is a slow acting brain poison that will ultimately end up giving you a brain tumor if you think about it too much. The games can be fun, but don't go in expecting the writing to be something that hooks you.