The hotel is located opposite the in a very nice part of Dublin, it is right across form the RDS. As other posters have mentioned it is more like a large grand house. The interior is splendidly furnished and staff were really helpful. There is a large room where you can relax in front of the fireplace on nice sofas and chairs, and have tea or coffee.Unfortunately i didnt have enough time to sit and enjoy it for long due tothe nature of my short stay.
The rooms are very clean, really well appointed and lots of room. The bathroom was very nice and a large jacuuzi bath which also i didnt get the chance to try out, although the shower was very good.
Breakfast was excellent, and an excellent choice on offer too, some of the fresh bread and scone loaf were great, followed by a delicious full irish breakfast.
There is a DART station about 3-4 minuts walk away, as well as good bus connections due to the proximity to the RDS. There are renovations going on at the minute due to the construction of the spa, but this had no affect on our stay whatsoever. there is car parking available at the rear of the hotel. We will definitely stay here again when in Dublin, especially for any concerts in the RDS. As someone else has mentioned, the hotel is small but has a very nice homely feel to it.

Right, first of all I would like to point out that lastminute.com does not point any of these issues out at merrion hall... So please do not be fooled by the advertisement.
We initially got set to the merrion hotel which is a beautiful 5* hotel to be told we were at the wrong place! Although I concede that could be seen as our own naivety!
We then arrived at the merrion hall guest house to be welcomed by high blue construction boards.. Let's just say we were taken down a peg or two!
The lady who met us was very nice and made us a cup of tea... Once I had realised that the room with a view was actually looking out at a half built spa I knew then it was time to leave.
After speaking to the owner who did his best to convince us to stay we then had a horrific 45 minute convo with lastminute to try and sort our situ out... Terrible customer service from them.. Seemingly a lady who I guess was in a call centre in India really didn't care about our demise.
We got a full refund and now are staying at a nice enough hotel across the road... May be it was the early start that made the beginning of this trip so difficult or possibly the horrific adventure we've been on since 9am this morning... It's 2pm now... Lets go get lunch! Things as they say can only get better...
Also think trip advisor should check their sources for who leaves this good feedback... Wouldn't be surprised if it were someone related to the business somehow!
Have a look at some of the pics!

Stayed in the Merrion Hall on 30-31 Oct, stayed over the weekend after a business trip. At first, the driver from by business hotel drove me to the Merrion Hotel, so please when travelling give the exact address of Merrion Hall, otherwise you might be driven to a different location.
There is a construction wall currently placed in front of the hotel, but the sign in front clearly states that the hotel is operational and is working normal. The entrance is now from the side street. The area is residential, so the hotel looks kind of a regular house, but dont be scared, it's very nice inside.
I was served by a very nice front desk guy, he escorted me to the room. The room was really cute, not huge, but very cozy, with couple armchairs, fireplace and old style bed with a valance. The bathroom featured jacuzzi, which unfortunately was not tested by me.
General feeling - great place, very charming, like grandma's house, cozy, so you forgive some very minor things, and it also felt very traditional English/Irish house, so definitely what was needed.
Breakfast was very nice, had a wonderfull porrige, again, like grandma's. Staff is really frendly and eager to help, so had no issues. The car to the Temple Bar area is about 10 Euros, which is not critical. The only thing which was not very comfortable with a large bag, was absence of the elevator, so please be aware. However, the reception guy was helping me with the bag, so ok. Also, the Merrion str. is not very quiet, many cars and busses till late evening, but it did not interfere much with my sleep, but some travellers might be conscerned.
Definitely would recommend to stay there, as it passes a very English/Irish athmosphere.

If it's boutique you want, look no further when staying in Dublin. Outstanding and a very engaging team welcome you on arrival and maintain this attitude throughout your stay. I was here on business and found the advertised facilities (broadband, coffee, work space) to be perfect. Good restaurants are only a short walk away and an €8 taxi fare will deliver you to your chosen den of iniquity.