Hiya! I've just finished my first year at cardiff uni, and although I didn't live in aberdare, my friend did and my sister also stayed there the year before too, so I thought I could have a go at answering! (although everything I'm about to say is just from word of mouth and from what I've seen when I've visited, so I could be completely wrong lol!
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The bathrooms are ok-ish. There's usually a lot of people sharing one bathroom coz the others are often broken (i think my friend said at one point there were 15 ppl sharing a bathroom), and hence they can get pretty messy pretty quickly. But then there are cleaners that come around frequently too, so usually mess is cleared up pretty soon so it doesn't often get intolerable.
I've heard mixed stuff about the meal quality lol. My sister always said the meals were ok, but then my friend hated a lot of them haha. Tbf there are always a few good meal options every week, and there are always vegeterian options. And you'll also probably appreciate having a hot meal ready and waiting for you after a long day of lectures as well.
I think it's pretty easy to make friends at aberdare! Certainly my sister and my friend made some lovely friends when they were there. Obviously like all student accom there will be people you clash with, and not everyone will be overflowing with the milk of human kindness, but that's the case anywhere really, i think overall there is a pretty good community in aberdare.
Room size depends a lot on which room you're assigned. There are some REALLY big rooms that are very nice indeed, but most of them are pretty average size. They're not super duper small or anything, they're certainly bigger than some uni bedrooms I've seen, but they're not exactly big either.
Overall, I certainly always liked the feel of the place when I visited, and I think it would've been my second choice for uni accom. It's really close to all the uni buildings, lidl is only 5 min down the road, the building's quite nice, there seems to be quite a nice community there and it's also female only, which I think would've been good. But at the same time maintenance work is pretty slow, the food isn't always great, there's usually a lot of people sharing a bathroom so it can get quite messy. I would also recommend that if you have an option for which wing to go for then you might wanna consider library wing, coz that sounds probably the nicest, but I haven't actually been there myself so I might be totally wrong lol.
Hope this has helped! Like I said I haven't actually lived there myself so I could be mega wrong, haha!
Good luck with everything!