Sailed with my daughter on
DCL when she was 8 and 10. Loved it both times.
That being said, she spent a fair amount of time in the clubs on the first cruise, and not nearly as much on the second. She was starting to get to the point of "I'm on vacation and want to lay in a lounger, read my books and listen to my ipod", rather than participate in organized activities.
Knowing that, when we sailed again last year (she was about to turn 12), we ended up sailing on the new NCL Escape. Since all she/we wanted to do was relax on sea days and she was interested in doing the evening activities with us (the shows/karaoke/dueling pianos/etc), it didn't make sense to pay nearly double for an oceanview room on DCL, compared to the large balcony mini-suite we had on NCL (large enough for 3 loungers, a table and 2 chairs) and the unlimited adult beverage package.
There was a teen club available to her on NCL, but my little nerdette was thrilled to have unlimited reading time instead (she's a tv-meh, books-yay kind of girl), so we can't comment on its quality.
All to say that DCL is great, but for what she/we were looking for out of a cruise, DCL no longer fit the bill for us. Sounds like you might be in the same boat (pun intended).