I stayed at the Aisling Hotel in April, of 2012.  Found it to be reasonably priced, comfortable, clean and conveniently located.  We had a triple and it was QUITE spacious.

The Hotel is a VERY short walk to Heuston Station.  From Heuston, there are numerous City Bus connections, a Pick Up and Drop Off for the Airlink (the airport shuttle) and a stop for the Luas (the Dublin, light rail Tram).  About the same distance away from the Hotel, in the opposite direction, is Collin's Barracks (a National Museum) and Croppies Acre (a personal favorite), and another Luas stop.  Also along this line is Smithfield, Four Courts, a stop just before O'Connell Street, Lower Abbey Street (with the General Registry Office and the Valuation Office) and the Main Bus Terminal.  Very close by to the Bus Station is Connolly Station and yet a different Luas Line.

I would be a little hesitant to walk along the Collin's Barracks area, late at night, as the area had a fairly 'dodgy' reputation, up until just a few year's ago.  With THAT said, I would NOT hesitate to stay at the Aisling, again.  It beats the noise and craziness down in Temple Bar, by a mile, in my opinion!

There are a number of hotels that are 'closer in' to City Center, but the recently refurbished Aisling IS close enough for me.  We found it to be nicer than either Jury's Inn (Christchurch and Custom House) that we've stayed at previously -- and more convenient than the old Burlington (now sometimes called the D4) or even Stauntons on the Green -- which was a LOT pricier, but nice, in its own way!

Hope this helps --

The (?) Bob

I stayed there with a CIE tour. It's wasn't my first choice BUT it was not a bad place. It was nice and close to HOHO (hop on hop off bus stop) taxis and other great pub/restaurants.... If you found a great price for it grab it. You won't be disappointed!

The Bob was a typo!  I'm sure you've been called worse.