Paxed on (EK) 380's for the first time a few weeks ago. Downstairs in economy just behind the wing on both sectors.
The aircraft is extremely quiet from there on take off, but there was a lot of vibration (I assume from the spinning wheels as they are retracted) until the gear was up, and quite a sudden "crack" of a noise, which I think was from one of the gear doors closing.
As the a/c was cleaned-up, the hydraulics driving the flaps were pretty loud also (like on the Airbus narrowbodies, but louder) but this might be accentuated as the background noise is otherwise so low.
The landing at DXB while not "bone-shattering" was definitely "firm" and there was a quiet a big accompanying noise (not quiet a bang, but quite loud).
Overall though, I was impressed with the space 10-across. You can tell it's a little bit wider than a 74' down there.
The IFE was also the best I've experienced, everything worked including the wifi and live TV. The food wasn't too bad either :-)