A380 - little things.
A380s have never figured on routes I've travelled until Tuesday when I came home from San Francisco on a BA example.
In many ways, I felt it was simply a big plane. We got a little turbulence en-route and it dealt with it well but didn't eliminate it (why should it?).
Two things I wasn't prepared for. One was the initial acceleration surge; there was a very noticeable initial push as we began our take off run, more than most aircraft. The second was the front cabin upstairs toilets (either side of the stairs) - by most airlines standards absolutely huge. However, those toilets have a problem for taller (I'm 6'2") men; the curvature of the fuselage and the placement of the toilet bowl against the fuselage meant I had to adopt a knees bent posture to stand and urinate - I seem to remember a complaint about something similar in 146s in California.