It's decent and it is quiet. However, I don't know if it's just my bad luck or this is just the way these things are, but I've RMAed one for horrible noise from the pump (cavitating due the air they leave in the lines, most likely) and the replacement isn't much better. I have it running at 70% capacity via my mobo's fan control, as at 100% I can hear it grinding and crackling over my case fans.
Still, even at 70%, it's better than my previous air cooler by 10-12C and at 70% it is DEAD silent. Even if it didn't have the excessive pump noise, I'd probably still run it at 70% to control the noise from the fan.
For $55 it's worth a shot.