We just sailed Deck 1 on Wonder earlier this month. We didn't have a problem with noise, motion, or anything. The worst part is that it is so far away from the pool deck (aka drink station, quick service, etc.). That was quite inconvenient. We, for sure, didn't want to forget anything in the room since it was such a hassle to go down to get it.
Elevators were easy to get, since by the time they made it down, they were empty. I don't think we had to wait any longer for an elevator on deck 1 than we did when we were on deck 5 last year.
I had the chance to book a different room after I booked deck one and chose not to. I wanted to experience deck one because you never really know until you try. Now that I've done it, I probably won't again unless it is my only choice, but do I regret staying there? NO!! I have no complaints other than being far away from drink station.
I say just do it!! and keep checking back to see if you can upgrade, because people cancel all the time and there is a good chance something will open up unless time has ran out.