I've stayed at five AC Hotels throughout Spain and Portugal and found them to be pretty basic. Generally the furnishings have been very modern, but almost sort of minimalist. They usually have a mini fridge stocked with some drinks. Since they don't have a lounge I've been told to help myself to the mini bar (I assume because I'm Platinum) a few times, but that was definitely the exception and not the rule. The same goes for breakfast. It's usually not been included and consist of cold cuts, cheeses, bread, coffee, and cereal.
Bathrooms have sometimes had baths, but sometimes (including the one in Barcelona) were only a shower.
Overall, I've liked them. But, I don't like the inconsistency of sometimes getting breakfast or sometimes getting the minifridge etc...
One negative is that most of them have lacked wifi in the rooms. You had to go to the lobby or a certain part of the hallway or maybe sit by an open window if you were near the pool.
Haven't been to Barcelona yet but did stay at the AC Receletos in Madrid twice. Here's a link to my review and hotel room pics from both stays. The pics will give you a feel as to what to expect.
We stayed at the ac hotel victoria last October.
i Thought the hotel was good.
We had a spacious room on a high floor that included a balcony area.
breakfast was good with a decent choice.
location was fine, close to metro station.
overall no complaints and we are staying at the hotel again in October.
barcelona is a great city have a good time.