I bought a nero at the end of November. So, been running a little over a month. It's on a 50g, 24x24x20, running it over 60% sends a wave of water out of the tank. I have it capping out around 40%. The first 10 days or so, it was ridiculously loud, as in I could hear it from the next room loud. No matter what I did I heard that pump, but after about the 10th day it went dead silent. I don't hear it at all anymore, guess it just needed to settle in.
I also have an mp10 on the tank and this nero is as silent as the mp10 but pushes so much more water. It's really awesome. I know many people complain about the wire in the tank, but it's a much thinner cord than any other pump I've had, so the cord practically disappears and the outer magnet is obviously way less obtrusive than the outside of an mp10.
Only complaint, and it's a minor nitpick, and only my opinion, but I wish the impeller was black instead of blue. The bright blue catches my eye, if it were black it would be less noticeable. I don't really see why they went with the blue, but like I said, my opinion. Haven't had any issues with the magnet but I've heard a few complaints. My glass is 10mm, and I'm planning an upgrade to a 12mm thick 80 gallon tank. Hopefully it holds as well on that tank. If it does then I will gladly purchase a 2nd.
All in all, 2 thumbs up!