I think different players are going to have very different opinions of ROTHC.
For me, as an example, I have one character that was Level 50 before the expansion so the extra content is new, exciting, and I still haven't looked at much of the old content.
Also I can play for maybe 2 hours maximum a day if I'm lucky.
For other's they'll have multiple level 50 characters and will have experienced everything the game already has to offer and so the expansion may well seem like too little to keep their interest.
It's all a matter of perspective.