I agree with both fermc_13 and promise2sweet about the ending being rushed, but even further than that... all of the chapters prior to the ending seem to only build up the setting and background information, rather than set up the ending to be open. It's as if the story was through before it just began. Because Origami wasn't set up to prepare for an open ending, it's quite difficult to consider it as one. However, it was very promising, so for the most part the ending didn't detract from my enjoyment.
Also, there were a couple of different themes introduced in the story, including the origami, one's ambitions, love, Yuna's mother's luck, and they were only loosely tied together. It's possible that they aren't well developed because the story was so short, so it would've been nice if the mangaka focused on just one or two in order to keep the story concise.
In short, if you're looking for some good raw material to read, I'd recommend it. Despite the setbacks I mentioned, it was quite enjoyable. If you're more picky, maybe this shouldn't be your top priority read.