I played this game years ago on my tablet and it was okay but at least in my eyes not worth buying it.
What was changed compared to the mobile version and what was added?
Is the game worth a buy over all?
Any experience?

Somehow I would hope for a new any maybe better settlers, but from what I remember from the mobile version, this would not really fit.

It's only slightly Settlers? Same family, for sure, but a distant relative. You build towers to defend against random bandits. Or at least that's all I've seen so far, but I don't see evidence for more on that side of it.

I've played through the tutorial levels, which have been very on-rails. [I'm not quite done with the last one yet.] I don't know yet how the scenarios will work out.

The UX has some issues -- such as you have to demolish terrain doodads (stumps, decoration, etc) manually before you can build.

It is very clear it may have originally started as a "mobile game": Allow purchasing of "crowns" which let you insta-build (without resources) buildings instead of only getting them as rewards for goal completion. Keep those timers ramped (such as when you're waiting for the merchant to return, or for research). It's playable now -- but it feels like it needed another smoothing pass to make it a standalone non-exploitational game.

I have enjoyed it well enough. I don't think it will have staying power though...

Full price? Not worth it. $12? *maaaaaaaaaaybe* meets my threshold. Less than 10? Definitely worth trying if you like the genre.

Revised: very end of the last tutorial ("campaign") level had you send troops from your towers to attack an enemy camp Settlers style, so that's there.

Campaign/tutorial did not quite cover every building, but enough of them to feel how the rest will go. However, there's still a lot of "tech" upgrades to get that (persist level to level) to increase efficiencies, and plenty of standalone scenarios.