I was surprised on this Cruise myself to see that the Serenity pool no longer specified by the Captain in his opening announcement as Adult only. To be honest on this cruise it seemed to me that most passengers still treated its as adult only, although I found no reference in signage or literature onboard that it was. Perhaps they didn't feel the need to specify it was as there were very few teenagers onboard. Last summer Captain Paul Brown was in charge and made it very clear that it was adult only. On this cruise Captain Wesley Dunlop only made reference to parents being responsible for their children at all times.
I find Britannia to have a fairly logical layout on the whole. I agree the Promenade deck (or lack of it) is disappointing and the Grand Class ships e.g. Azura have far better Pool and Hot tub arrangements, with the exception of the Serenity poo,l which is far superior on Britannia if a little lacking in shelter.
I also prefer the Glass House on Azura, as it feels like a much more defined space with a decor that is far more individually styled, which makes it stand out as a proper wine bar. The Blue bar just doesn't work on Britannia, it is completely soulless, whilst it feels like a premium bar on Azura, with a the pianist centre stage. It seems like they have wisely given up on having a pianist, as you can't actually see them from the bar itself. It was pleasing to see they are now positioning some live music on deck 6 so you can actually hear it from the bars on deck 7.
Everything I have said so far suggests I prefer Azura, however despite finding her a fine ship, I find Britannia far more coherent in design than Azura and rightly worthy of being the flagship. The rooms and their balconies may be smaller but they are far more contemporary and feel sophisticated. Azura's rooms are a good size with excellent balconies but they are dated in design. The same can be said for the Grand class ships in the Princess fleet.
The buffet restaurant is the best of any ship I've been on for its efficiency, it genuinely feels like a nice place to be (Normally I avoid the buffet at all costs as they so often feel like a Motorway services). It also works far better than the Lido's on any of the Cunard ships, including the new layout on QM2. The general decor of the corridors and public spaces, e.g. the Crows Nest, Crystal Room, Limelight Club (now open for free, for live music after 11pm to adult guests) are a class above the rest of the fleet and better or equal than those on Cunard ships. I'd agree that unlike the restaurants (including the Glass House), where service was excellent bar service was often slow and unimpressive compared two my experiences on Princess.
As we arrived home QM2 was in port and it made me think, which ship would I rather be leaving on tonight? I honestly could only choose based on itinerary. Of course transatlantic, give me the proper ship (QM2), the Med give me the Cruise ship (Britannia because if you stepped off the recently refurbished Cunard flagship on to Britannia you would find the Staterooms/Cabins perfectly comparable and the decor of the ship as a whole as equally sophisticated. Of course QM2 feels more traditional with Britannia being more contemporary.
I must say like Grand Class ships a lot, I'm booked on one this summer (Caribbean Princess), so I have no issues with them at all. Of all the ones I've been on Azura is by far the best. In my view it is the second best ship in the fleet (Aurora gives it a good run for its money) and I can't wait to sail on her again soon :) If I had to sell P&O to a customer from RCL, Celebrity or NCL I'd pick Britannia to show them the line at its best.