Excellent little fan, the blades are in fact metal, and it is very quiet. I don't think it would be useful if you need to move a large amount of air, but for standard cooling purposes it's perfect blend of cooling and noise. Using it to cool a LSI 9217, and it's perfectly fine. Only negative is the lack of a sense wire, but I could have ordered elsewhere for that, and don't need one. Also note that the three tabs that hold the fan in the frame are rather weak, at least if you need to push on the fan itself when installing. That's normal though.
Ordered 2 - both have some vibrations. not too much, but it makes them louder. around 50mA on 12V