This was our first time on an Oasis Class ship. Embarkation was smooth but we had a Junior Suite with a separate area for suite cabins to wait for boarding. An announcement was made while waiting, encouraging guests to download the "passport app" for quicker lines at customs for our return. Very easy to use, we entered our purchases information on the app the morning of our return back into port. Received our OK Confirmation from them on our phone within a minute. We always use a porter and he took us directly to where we needed to go. Once we had our luggage it was maybe 10 minutes before we were out at the curb waiting for our shuttle pick up.
The Allure is HUGE...but we didn't feel that there were over 6,000 guests on board. I did hear someone say though the pool area does get crowded with guests on "Sea Days". We didn't use the pool area but can imagine it would be for those seeking direct sun.
There are so many venues, variety of musical options and shows in the evening. Guests were dispersed throughout the ship making it feel uncrowded. There were plenty of parades and performances for the kids during the day...it is a ship for all.