score:2
In such a situation, one advantage of the lower deck, if you can get a seat towards the front, is that you will most probably be out of the plane quicker.
This can be important if you have a short connection at the destination of that flight (whether it is another flight, or a train or bus). Being out quicker also increases the chances of smaller queues at passport control, if relevant (by far not a guarantee as it depends on other arrivals around the same time, but it’s nearly always better to be among the first of the several hundred people coming out of that aircraft than among the last).
Note that if you are not really towards the front (close to the exit doors, to be precise), then it’s a lot less obvious which is quicker: premium cabins have a lot less people, who are a lot more used to travelling, so they empty a lot faster than coach.
On the other hand the upper deck is slightly smaller (in economy the layout is usually 2-4-2 on the upper deck against 3-4-3 on the lower deck). This means less middle seats, less people to annoy when you want to stand and are sitting at a window, less people to annoy you if you are sitting at the aisle on the left or right sides…
In some cases the whole compartment is also quite small (limited number of rows), which makes it more cosy and you sometimes get better service. It’s not as cosy as it was on the upper deck on 747s of course.
Note that cabin layout varies a lot on A380s (even between different aircraft of the same airline: some have 3 different layouts!), so the details may vary.
Upvote:2
I have a strong preference for the upper deck.
Same argument applies to the upper deck of the 747 (if you can still find a 747 AND economy upstairs). British Airways used to fly this configuration and upstairs window seat was by far the best economy seat on the plane.