Adonia has 355 cabins in six categories. Only 24 are inside, while 72 have windows, and all the rest have balconies. Cabins are somewhat compact at 165 square feet (insides and window-only accommodation) and 214 square feet (balcony staterooms, including the balcony), but they're comfortable enough; big mirrors create a sense of space. Our balcony cabin on C deck had an impressive amount of storage; I kept finding more and more drawers and cupboards. There was plenty of hanging space in the wardrobe and a generous number of hangers. U.K. power sockets have been added, and there was no shortage of them; the old American sockets are still there, too.
P&O Cruises hasn't changed the cabin decor from Royal Princess days, but the mainly blue and white colour scheme, with accents of dark wood, hasn't really dated. Bathrooms are tiny, each with a narrow shower stall, clingy curtain and old-fashioned hose-type hairdryer above the loo. Toiletries, though, are really good: shampoo, conditioner and moisturiser from the chic British brand The White Company (no relation to Marco Pierre White, the line's celebrity chef).
What has been added to each cabin is a tea tray, with cookies and proper mugs for tea -- most welcome. All cabins have flat-screen TV's, and each balcony cabin has two chairs and a small table. The TV's show a variety of international channels and a rotating programme of movies, documentaries and comedies, with a reasonable choice. But in the Norwegian fjords, where I was cruising, there was very poor satellite coverage, and watching the news was almost impossible.
There are four forward-facing suites (AB grade) and six Penthouses (AA grade) occupying the aft corners of A, B and C Decks. These are significantly bigger than the balcony cabins, at 753 and 930 square feet, respectively, and come with all sorts of extras: butler service, full bathrooms with whirlpool tubs, separate guest WC's, separate lounge areas; DVD players and mini-stereos, proper steamer chairs on the balconies, atlases and binoculars, fruit, flowers and Champagne on arrival. The difference between them is that the four suites have curved, forward-facing balconies, while the penthouses have balconies that are more of a wraparound style, with bigger sunbathing space, which makes sense as they're located aft, in the sheltered part of the ship.
I liked my cabin very much in terms of space and the state of the decor. Others were less impressed, complaining about worn woodwork, leaky bathrooms and tatty furnishings. If you're comparing this ship to the younger vessels in the P&O Cruises fleet, the cabins may seem unexciting. One thing that would certainly be nice is glass doors in the bathrooms instead of clingy shower curtains; these bathrooms really are very compact.
I requested bathrobes on the second day of the cruise. My cabin steward explained that these were for suite passengers only but that he would try to find some, which he duly did. It never hurts to ask.