I find Call of the Zone excellent in every ways.
It does not have any features i don't like (unlike some other mods) and look and play really well.
Additionally it load faster than nearly every other mods (i guess not using truckload of super high res textures everywhere helps) making quickisave/load completely painless
Also seems rock solid, only crashed once (in fact it was on my first play) but since then not a single time (Call of the Zone has been updated to 1.1 by the way).
I'm on my 9th day of hunting artifacts around the map and making tons of money from selling them to either Sakharov or the Jupiter scientist in their lab, even got the achievement that is increasing the respawn rate of those artifacts.
This has been helped by the fact Sakharov on my first day gave me a random task to find an artifact (that after checking the file can only spawn in Generators, that is the most far away map/area) and "to help" he also gave me ... a svarog ... for free !
Looks like those dynamic tasks may need some progression rebalance a bit as the svarog is the ultra highest end of the artifact detector series (it also display all the anomalies, making it very easy to navigate inside clutters of them to fetch artifacts in the middle) and should really not being that easily available to the player (as it fully bypass the need to find the normal detector then the bear and then the veles).
But at least it helped me swim in money from all those artifacts i sold
Had some nicely great large firefights too, some Duty random missions lead me into battles with Duty squads and their enemies (mostly Monolith as with the random faction relations we got Freedom neutral)
For all the stalker standalone mods based on freeplay, Call of the Zone is the very best for me, there are addons starting to get added on the moddb page.