I have never sailed concierge on other lines, but one of these days I swear I'm going to splurge! From researching, it seems concierge prices on other lines like NCL and RCCL are considerably less and offer far more perks/amenities.
For example:
March 4th, 2018 7-night Western Caribbean cruise on the NCL Getaway. 3 people in a Haven courtyard penthouse w/ Balcony & King size bed (386 sq ft incl. balcony). Total is $6,670 US (that includes free specialty dining, free drink package, $50 excursion credit per port, and 250 internet minutes). The Haven concierge level also gets you exclusive access to The Haven Private Restaurant, Sundeck, Courtyard, & Lounge, concierge service, and a 24-hour certified butler.
March 3rd, 2018 7-night Western Caribbean (with Star Wars day) on Disney Fantasy. 3 people in Concierge family stateroom w/ Balcony & queen size bed (306 sq ft incl. balcony). Total is $11,001 US. That includes exclusive access to the Concierge lounge, Sundeck and concierge service.
So it's up to those who book to decide if it's worth the extra $4000+ to have access to the Disney characters and shows, and for some that is the most important part! I think no matter which line you sail, if you are in concierge, you will be spoiled!