So i bought this plugin just to shred Shadowpauler's review below.
With all of the complexity that iris has to offer it is REALLY an engine.
I've been with iris from the start(literally) and have used it from practically every state it has ever been in. From absolutely broken, to typo's it has had so many growing pains as a software. And amidst all of the problems the development turn around for them is ridiculous.
Iris offers more than any world generator in terms of customization. Terra is great, but lacks many of iris's Critical features.
Iris by default is NOT an Overworld , Iris is NOT an Overworld generator and rating it as such an ignorant take(Shadowpauler) Iris is an Engine and ratings should be as such. Iris starts off as a Flat-Grass world, and EVERY SINGLE LINE OF CONFIGURATION is what creates a world, and they have a public Overworld pack that they manage, and allow you do download should you want it. So if you are basing any rating of the plugin on the worlds that are publicly available you are absolutely off your rocker, as that is reviewing the wrong software. For that you can go here
https://github.com/IrisDimensions/overworld
So if you want to make your world 100% from scratch, iris does that with more management, hooks, and implementations that i have ever seen in ANY plugin on this website; including Terra.
Also: I would never rate someone's software on the basis of how independent members of the community respond to me leaving intentionally poor reviews on my competitors software, but if i did my name would be Shadowpauler