This is a very elegant solution...one could attach a hose instead of a water bottle, btw, and lead it to a larger catch basin.
First I can't really see how it works, just from these pictures. Second, even if it does work, I don't see much practical application. Hundreds of these versus one large water butt? I'd like to see the sums that show these are cheaper. Also if anywhere is rainy enough to need gutters, I'm thinking water isn't really an issue for them.
but will the raindrops really be 100% clean?
Don't plastic water bottles start to shed chemicals into water when they are reused multiple times?
And watch the downspout peel away from your house....
If made to a sufficiently durable standard, this could be a good invention for areas that have trouble finding fresh water.
I don't believe it will revoultionise water collection or anything, but any step in the right direction like this can only be beneficial.