Yes, you get a couple of cabin perks such as a travel bag or a footstool outside but when I think of Concierge class, I think of service and I can't see that it really provides anything worth the effort. Yes, you have a concierge desk you could go to and they would happily assist you - up to a point. For example, a big push is that they can help you with shore excursions or activities. For sure they can book an excursion for you if you know which one you want. But if not sure or have further questions they refer you to the shore excursion desk.. so why not just go there first ? I had asked if they could make reservations onshore for us or find options for us onshore for a specific activity and they suggested I search the internet myself. Yes, they will gladly make a dining reservation, but really ? I can do that from my stateroom on the TV or on the phone.. Why would I go to the concierge desk for that.
Repeatedly they will leave messages for you regarding how much they want to help you enjoy your cruise, but nothing is offered that I could not do myself easier. Yes they leave canapes in the afternoon - but I have never enjoyed them. Some strange stuff there. We typically just ask our room steward for some afternoon cheese and crackers and they always happily provide this. Even without a concierge cabin.
So again, the concierge at a nice hotel or resort will resolve issues for you and take steps to help you enjoy your stay. But I have yet to find where this service provides anything that is not easier to do myself vs walking to their office and waiting for an available concierge.
So short answer is no - I would never pay for a Concierge cabin, if it was a free upgrade - whatever.... foot stools are nice to have.