The noise has been discussed a lot, and everybody has to form their own opinion. "Noise" and sound comfort is extremely subjective. Personally, I have a background and a career in audio, so I try to protect my hearing as much as possible/reasonable. I just had it (my hearing) tested Monday, and its above average for my age, which may actually make me more sensitive to genset noise.
I disagree that it's like a lawnmower, but yes, its definitely a low roar. If I started my lawn tractor next to the 002, then started the 002, I would no longer hear the lawn tractor. The lawnmower may still be more *annoying*, though. The consistent and low rpm of the 002 makes the noise easy to acclimate to and tolerate, affecting the perceived loudness, but its not in any way quiet. I'm certain you'll hear the 002 at a distance long after the lawnmower has become indiscernible (low frequencies travel further anyway). If you're in a development with 1/3 acre lots, your neighbors will absolutely hear it and probably consider it annoying if they're grumpy.
Time of day is also relevant to perception. It's not noisy at midday in a city, but it's the loudest thing in the world at midnight in the country.
That being said, if you put it in a shelter, especially a large insulated shelter with the insulation on the interior and an air gap between it and the outer wall of the shelter, that will help a lot.
I say large because much of the noise with it comes from combustion air intake, cooling air intake, and exhaust. The rotating assembly and block harmonics also add noise, but moving air turbulence is probably the bulk of the radiating noise. Since the genset needs all that air to run, its hard to control it. A large insulated space allows all that air to be turbulent, while absorbing much of the vibration within the containment. And then, its best to vent the shelter at the top so that what noise does escape through those necessary openings, dissipates in the atmosphere, rather than reflecting off objects that eventually reach your ears.
Eventually, I will find the dominant exhaust frequency and add a stub to null it, but that won't help the clean air noise.
Short answer; their "noisiness" is very subjective and different people will have different answers that you may find completely wrong.