It really isn't. 47% increase on a tiny sensor is still a tiny sensor. It's not even double the size.
That's not to say it won't be an improvement, but if people are expecting this camera to suddenly become the best thing since sliced bread, it is going to disappoint a fair few... especially when you have to ask, if photography is that important they could get the regular iPhone 12, or even a 12 Mini and buy a dedicated APSC mirrorless camera or even something like an RX100 point and shoot which requires no real knowledge of photography. It's not just the size of the sensor, but the quality and size of the glass in front of it. Decent camera lenses cost more than an iPhone - so there's no way it's ever going to come close (if you know what your actually looking for), but as said for most it will be perfectly fine and computational photography has come a long way from what it was, which helps a lot.
I can guarantee that when you zoom into the photo or look at the detail you'll notice it has the same appearance as a water colour, a bit blurred where the iPhone has heavily reduced noise (grain) and destroyed any detail that was there.
Less so than the regular iPhone and regular Pro model, but if all you are doing is posting on Instagram, Facebook etc then your very unlikely to even notice a difference anyway when viewing on a phone screen - so for most it will be fine, but also I don't think side by side there will be a big enough difference (personally), but I am happy to be proved wrong.
This is something that hopefully Pro Raw will address (in reference to the auto noise reduction the phone does to your photos), but still no one knows anything about it really yet.