The Allure is huge, so even being at almost full capacity (6,100 passengers), it didn't seem too crowded. There were lots of kids on spring break, and I'm not sure we would choose that week to cruise again.
The most impressive thing about the ship, besides it's size, is the ability of the ship and crew to manage the population efficiently. With very few exceptions, there were no crowds or lines. It was easy to find places to sit in public spaces. Embarkation was smooth.
Some random notes:
We had 2 adjoining inside cabins. They were both in excellent condition, but our room steward was the worst we've ever had. He never introduced himself and always seemed to be in a bad mood. If we came back while he was in the cabin, he made it clear that he was annoyed. We would often return after noon and our room was still not cleaned, despite putting the tab in the door to indicate we were gone.