Our 9th annual spring break cruise with our kids (15yo) and several other families. We sailed Indy in 2014 as well, and were happy to be back on board. We have sailed Royal and Carnival multiple times for spring break cruises.
Our favorite thing about Indy is the staff; for some reason, they are better on Indy than on the other Royal ships. It was the case in 2014, and was still the case this year. I have not cracked the code on why that would be the case, by the way. We noted this year that more staff is from the Caribbean rather than from Asia. But the staff in both 2014 and 2016 was better than other Royal and Carnival ships we have sailed, to be sure.
My least favorite thing about Indy is the lack of a true headline Broadway show. Royal needs to get its product consistent: Liberty (same class as Indy) has Saturday Night Fever, also on shorter length cruises. But Indy...nada. We saw a very good comic, and a very good ventriloquist. But the lack of a Broadway offering on Indy is bothersome.