Looks like a fine and functional, if not overtly beautiful system to me.

At some later date you might upgrade to a simple first-flow dump and strainer system to limit how much dust and detritus gets into the tank. It keeps the water a good bit sweeter and reduces the need for tank cleaning.

First-flow dumps can be mechanical tilt mechanism , or even a float valve but IMO the best ones are simply a small, a gallon or so per hundred square feet roof area, of dead storage that get filled before the water overflows to the main storage. When the rain stops this small tank drains by way of a small hole so it is automatically ready for the next cycle. No moving parts is good for reliability.

The strainer is ideally set up to be self-cleaning and, because the first flow depends on a small drain hole, is best placed before the first-flow unit.

Sounds complicated I know but these units can shift a rainwater collection system from being primarily landscape watering and toilet flushing, drinking if you're in dire straits, certainly useful enough to justify the system, to a supply of water you can drink and still maintain a smile.

I think its a grand idea to have every house equipped with a rainwater collection system. It is smart to conserve what we have and, if and when the municipal water fails for a few days, everyone has a reserve.

For areas where freezing is an issue the cistern/s can be placed below the freeze line and the plumbing can all be set up to drain so there is no trapped water to freeze.