My partner and I stayed at Ranga during the last week of January 2012. We found it to be extremely welcoming, relaxing and beautiful. The hotel itself is simple in appearance, but the rooms are well appointed. I suggest getting a room with a view of the river. We also had a room with a large bed and a jacuzzi tub - many rooms have two single beds so be sure you ask for the larger bed and better bathrooms. We really enjoyed the amazing outdoor geothermal hot tubs! It was cold and sometimes rainy while we were outside, but the tubs are incredibly warm and relaxing, so don't feel that bad weather should keep you inside! As we were there for six nights we had a lot of time to explore the area. If you want to go on some great day trips I suggest the tour of the South Coast with its amazing black sand beaches and lovely white foamy sea. The Golden Circle is also impressive, though has more tourists. We hired a superjeep tour guide named Sæli (info@southadventure.is) who took us on some amazing side trips and really made the days interesting!
We didn't really see the northern lights, only through the clouds one night, but they did ring us to tell us they were visible and we were room 48 so I'm not sure why so many reviews seem to suggest that they don't call the rooms at the end of the list.
As we were there six nights we had ample time to enjoy the restaurant. Breakfast is lovely and goes until 11 so no need to set an early alarm. You've got eggs, sausages, bacon, waffle maker, pastries, meats, bread and cheeses as well as all the beverages you might need. The only thing that was a bit low was the fruit selection, but that may have been the time of year as well. The dinners are really nice and the food is expertly displayed. The meals seemed to have a standard format - all came with the same pureed potatoes and mixture of "root vegetables" (peas and mushrooms...) and had a changing protein and little extra flair - for example the salmon also came with a few sliced strawberries and champagne foam. There is also room service which can be from the restaurant menu or the room service menu which is quite small - just burgers, a sandwich or soup. We had the burger one night though and it was just fine, and cheaper than the restaurant!
A few more tips... if you don't hire a car it is tricky to get there. You can get a bus from Mjodd in Reykjavik (takes about 1:15) and you need to ask the driver if s/he can stop outside the gate of Ranga. It is far too far to walk from the stop in Hella. The hotel very nicely arranged for a staff member to collect us from the gate and drive us the 600m or so into the car park as it was very dark, rainy and windy. The hotel manager was lovely and walked around at dinner checking in with all the guests. The rest of the staff were helpful and welcoming as well - but do put the "do not disturb" sign out if you don't want them to come in as they seem to operate a bit of a "knock whilst opening" approach like your mother would have done when you were a teenager!
All in all an absolutely fantastic time. Certainly exceptionally expensive but very much felt worth it. Enjoy!

Great food but that is about it sadly. Reception staff were lazy, didn't want to help with issue with room and they did not give call for lights activity, so we missed them which is the whole point of the place so. When I asked why did I not get a call I was told that they have too many rooms to call and so it was my fault.

Sorry but the whole point of this place is the northern lights and they do not provide the service they say they do. So if you want good food then great, otherwise avoid.

We arrived later than expected and the staff organised a lovely meal for our coach party(31 people) We were given a very informative presentation about the aurora borealis...although very sadly they didnt appear for us! The room was clean with comfortable beds and too warm for us but luckily we were able to turn off the radiators.Even though our room,26,was near to the reception,it was quiet at night.Breakfasts were very good with a very good buffet with lots of choice from cereals and toast to eggs,bacon.waffles and even bourbon biscuits!! Overall we had a comfortable two nights at this friendly,welcoming hotel.

Stayed her for 3 nights from 7th to 10th Feb. Hotel was nice and personal with staff being very friendly and letting us know when the Northern Lights were out on display.
Lucky to see them at 8.30pm and then again a magical display at 00.30 on the Tuesday night.
There is no light polution as the Hotel is in the middle of nowhere. They even turn off the few lights they have in the car park to make the area clear.
The food was nice, averaging about £22 for main courses and then you can add to that what you want for starters etc;.
The breakfast was a good choice of self service cereals, fruit, cooked hot food and the traditional continental selection of cheese and meat.
There are three hot tubs but we didn't use them.
Spent most of the days travelling out to Vik with its roaring sea and waves the size houses.
Makes a good base for the golde circle, waterfalls and Geysirs.
Our first night was at The Blue lagoon clinic and that was the exceptional for atmosphere and relaxing in their private lagoon.
Would recommend it as a base and would go back there - we booked through Discover The World and though it took a while to get things finally booked, the price was cheaper than we could negotiate.