If you are staying for a conference at the CCD (Convention Center Dublin) I would recommend staying with Alberto. Their place is a quick and safe walk to the conference center- even alone at night. The place is simple and clean; it has all the basics- including a wall heater for the chilly Dublin nights.
The toliet can be a bit difficult to flush but I figured out how to do it after a day or two. The shared bathroom was spotless as was the private bedroom. Alberto and Francesco were very friendly and approachable if you wanted to be social but still respected your distance otherwise.
The only other thing to mention is that one of the neighbors in the building occasionally screams as he has mental health issues. He did this on the first night I was staying there and it was jarring. Francesca (Alberto's partner) was very understanding, apologetic, and quick to reassure me that he was harmless, albeit noisy. He quieted down after about 20 minutes and made no more noise for the rest of my visit. I wouldn't want this to stop anyone from staying with Francesca and Alberto as their place is great- but it is something to be aware of.