The only thing about it and I'm not too sure about is the "rain cup" and what happens when it snows?
Just whatever snow you get piles up in the bucket until it gets warm enough to melt. Shouldn't be a problem as long as you're not worried about accurate readings. Shouldn't freeze and break or anything.
Or, as mentioned above, you can buy a rain gauge heater from Davis, or look at various threads on these forums where people have made their own. But from what I've read, they're not very accurate either, I guess a lot of the snow will melt and evaporate before it makes it to the cups. Plus you'd have to get power to the heater.
Or you can cover the bucket with a small rubber stock bowl, or a dog bowl, or whatever fits. That's what I usually do as I like to try to measure and log the moisture from snowfall manually.
I can't say how often it will need to be cleaned, depends on how many leaves you have blowing in, insects you have building nests in it, birds leaving droppings... I'd try to leave it fairly accessible.