Returned from the Anthem on 9/15 (Canada/New England). No guarantee that your cruise will be the same. I saw very few children on this cruise so that may have an impact.
If you don't get your reservation in before sailing for iFly, North Star, shows, dining, etc. don't panic. There were plenty of options available through the Royal IQ. If you didn't download the app, there are plenty of kiosk.
Get the coffee card. Anthem lets you get any size per punch at the specialty coffee stands to include Starbucks. 15 punches for about $36 with the added fee. Venti Mocha or Cafe Americano for me every morning. You can share the card. (again, make sure this is still allowed so best if you buy on board)
Go ride the bumper cars on embarkation day before the muster drill. We rode multiple times without having to get out of the car.
If interested in the Escape room, book as soon as you get on the ship through the Royal IQ. They go fast. But...I was told by the staff that they have a lot of no-shows so if you don't get a reservation find out the times and stop by. There's a good chance you'll get in. They start promptly on time though and lock the door. 12 people per session. Other ships are charging $20, but still free on the Anthem.
Ride North Star. Even if you are afraid of heights, you'll be fine. My wife is afraid of heights and has vertigo and she was fine (after a lot of convincing). We rode at sea and in port. We had one reservation and were able to get on again in the standby line. Toward the end of the cruise there are more opportunities. Plenty of slots open to reserve once on board. You can only reserve once though.
Ripcord by iFly. Just do it. It's amazing. Don't be scared, the staff know what they are doing and will keep you safe.
Okay, here is a secret.You can only reserve once on the Royal IQ (or online prior to the cruise), however, on day 6 (9 day cruise), you can go to the iFly check in and reserve a second with them directly.
Dining (I wasn't a fan of the food), the line for those with a reservation was just as long for those without and everyone was seated fairly quick.
I enjoyed the entertainment, a little cheesy at times, but fun. We will Rock You is a little dated, but fantastic talent and who can complain about Queen. I'll stop there because there are always mixed reviews for the shows. Still plenty of openings once on board.
Hope this helps!