I have one in my 4runner and another in my wife's Camry. So far not so bad. (Although I have been confused as to why they have the air flow in the direction they do. It seems to me the blue side screen would do a better job of blocking the large debris like bugs and leaves.)
All in all it's not too bad. The instructions are written in Japanese. The drawings show that they are simply rinsed out, allowed to dry, then replaced. I have only had to rinse them out once each after having them for over a year. They don't clean that easily and take forever to dry. Additionally, the material does not suggest they'll survive many such rinsings. But, if I get another year out of them, then they will have paid for themselves. The stock ones only last about a year...they get filthy fast.