I just returned from the Grand Britannia cruise with my mom, sister and daughter. We had adjoining staterooms. Here are my thoughts:
The good: Overall food quality was very good in all venues. We loved Prego and Silk Road, liked the MDR, liked Lido, and liked Trident. We got room service breakfast several times and that was also good. And we had WONDERFUL service in the MDR and in Prego, very fun, warm, and caring servers (Nikola and Stanko in the MDR). We also loved the Avenue Bar and their bartenders. We liked the overall itinerary as well, circling the UK.
The bad: I am in the camp of those who feel the veranda staterooms are cramped and very worn. The "couch" was stained, the carpet coming up by the veranda door, the chair ripped, the throw pillows disgusting, and the design of the lights in the headboard absurd when the beds are twinned. The veranda was dirty and sticky (they cleaned it our last day). The cabins were also not wonderfully cleaned, with extraneous hair and an old shampoo bottle greeting us at the start. Not fun.
Small, cramped, worn, difficult for two especially with twin beds. Not a good experience.