Did a trip on Navigator recently with 2 wheelchair bound passengers - Not a problem from start to finish. Lots of room, ramps, crew willing to assist if requested. The wheelchair accessible staterooms are absolutely HUGE compared to 'normal' staterooms in the same category.
Don't worry, you'll have a ball.
I assume that you have read all the information on the royalcaribbean.com page - under 'all about cruising' then 'accessibility onboard'. RCI have some of the best equipped ships in the world and because of this you will find several wheelchair-bound passengers on board.
I also suggest that you go to boards dot cruisecritic dot com and then scroll down to the section headed 'special interest cruising' and click on the disabled link there to find out more.