Hi! I went on P&O's Iona for my first cruise with a friend this year, and honestly loved it. I am not typically a cruiser and have travelled a lot, and do think some of the comments criticising Iona/P&O maybe come from people that have cruised tonnes - I don't know.
Ultimately, one thing I love about P&O is the price difference can end up being massive. Compared to more American based cruise lines, drinks are very reasonable - we got a package which was great but without the package, drinks were pretty reasonable honestly and there was a lot of choice. Another huge one, there's no additional tips required! Look into Princess for example, you will get an amount automatically added on to your bill every day for tips. So alongside the cost of your cruise, that gets added on top which is honestly extremely off putting to me. I want to know what the real price is when I pay, not have tonnes of extras. Due to this, I'm very likely to choose P&O again for a Caribbean cruise as the price difference is just insane when you factor in tips and drinks.
Iona was great - its a cruise, so food is not always perfect but generally we ate really well. There's sit down three course restaurants for breakfast, lunch, and dinner, and a few places for quicker bites to eat like fish and chips (which honestly, we actually really liked - and I'm a food snob!), buffet for really easy food, and some other restaurants you can book. There's different bars, and they sometimes have unique cocktails (Anderson's had a gorgeous apple mojito which I loved!), some bars do live music, some are big and some have a more cosy vibe. There's plenty to do on the ship - spa, events, quizzes, crafting, movies, swimming, shows.
When it came to booking dinner, honestly we had very few issues. I don't know if we just have more patience, but there's four sit down large main restaurants for three course meals and we never waited more than 30 minutes max to get a table. If the app doesn't work (it did for us, in browser form) you can go to the desk at the restaurant and request a table too. For the limited space restaurants like the Olive Grove, I'd actually advise checking these out on the first day when you board as no one is there (and then maybe booking for another day manually at the desk if you like it). If you truly had a long wait there's the easier more casual options.
I'd definitely do Iona again and honestly I'm even more encouraged seeing how expensive things like drinks are and how many hidden charges are added on other cruiselines.
