Definitely fits within Vanilla+ worldgen content mods

What is it ?

Ecologics is a mod making small additions and extra content to existing vanilla biomes which fit within Minecraft's core principles.

What does it offer ?

New content to often commonly-found biomes in the form of new trees, peaceful/neutral ambient mobs with extra uses and some more decorative blocks.
The mod also features new foods now.

Here's a list with every biome types and the changes they received :
The Desert
Cacti fruit type (added in vanilla recent versions as a form of cacti decoration, they go even better together now), ruins with pots of loot, Camels (before MC added them)
The Beach
Coconut crabs, sandcastles and blocks out of shells found on shore
The Plains
Walnut tree wood type instead of relying on oak trees again, squirrels
The Lush Caves
Azalea wood type instead of relying more on oak, stackable & surface moss (stackable pale moss was added after the pale garden drop); The Azalea wood type was added there before Minecraft featured other pink planks in the form of cherry wood if I'm not wrong, another point to Ecologics I guess
The Frozen Ocean/Snowy Areas
Penguins, weaker ice (similar to the way they added it in base Minecraft in post 26.4, even if not exactly the same), Ice/Snow bricks, potion of sliding

Since 26.3 they added Maple trees and syrup to extract from them (appearing in various specific biomes)

There isn't much more information for me to give as everything is already documented on the mod's page;
I especially like how most if not all additions are not just aesthetic, but serve a secondary purpose (like how Sandcastles can be used to defend turtle eggs , or how squirrels are indeed ambient mobs but can also be tamed )
Giving more than one purpose to one thing within a game helps to make this thing feel less disconnected from everything else, and this interconnection is one of the reason this mod works in Minecraft the way it intends to and participates in the systemic game that is/could be Minecraft (that cannot be said to even some vanilla features).

I have not noticed any particular issue, the mobs have their own sound effects, the textures are nice and consistent and I haven't seen any performance problems myself.
I used to think the desert ruins structure appeared too often but I see now that they acted on it and reduced it, making it less overpowered than before and it is a change I'm glad they made.

In conclusion

This is a mod I personally like a lot, and which is very good at adding what I would consider Vanilla+ content.
It doesn't add a ton and it's not crazy, but it doesn't have to, as its focus is different from other more explory worldgen mods I have seen before.

Like mentioned before I believe it works better in Vanilla+ settings, accompanied by other biome-overhauling mods such as famous mods Biome Makeover or Environmental, No Mans Land etc.;
Just try to avoid overlapping content (thankfully this mod's config file allows to disable the mod's various worldgen elements, to at least prevent this kind of compatibility issues from there)

I'm wondering what kind of content they will add next, and am glad to see they keep making updates to that mod