For a new dev working with an unfamiliar engine, this is really respectable work. Is it optimized? Big no-- huge file size and you need a high-performing system. Is there content? Well, that depends on what you may consider as content for a game like this.
There isn't really too much to say when it comes to the 'mini' gameplay. You get a few options to make the experience more diverse, and the vehicles and AI can be surprisingly immersive. But... There aren't a ton of animations, and the ones available aren't refined or satisfactory, in my opinion.
You also have the option of controlling and playing as the giantess, and this is where the game really shines. There are lots of giantesses to choose from, and there are also size-altering options. It's a little clunky, but not at all unplayable. Not really my thing, but it was pretty fun to mess around with.
As a mini, it feels like you're not really interacting with the giantess AI-- you're watching the AI interact with the world. And this seems to be in line with the development direction. Basically getting cucked, except instead of by a human, it's the world (wow).
I'm hoping that animations will be a higher priority in the future updates, as this (withholding performance issues) is what noticeably dragged down the game while I was playing.