We stayed for 2 nights at the apartments. The rooms were tidy, although the people who used the apartment before us didn't wash any of the provided kitchen utensils so we had to wash everything before we could use it. We were given one dishwashing tablet, a small container of milk, and a variety of cereals.
Heating/cooling wasnt a problem - in fact, we found the room to be quite cozy with a few heaters on.
The choice of making a room either a twin or a double is simply the difference between whether the 2 king single beds are pushed together or not.
Shuttle bus is unreliable. We managed to get it into town on our first day, then waited 1/2 an hour in the wind and cold for our return bus to the apartment. We ended up giving up on the bus and catching a cab back (costing about 10 pounds). Turned out the bus had broken down during its 4pm run. I overheard a number of people in reception complaining about this - one woman had her elderly mother there, so without the shuttle bus, they were basically house-bound. The staff's view on the bus is that it is a 'complimentary' service, so they are under no obligation to people who are relying on it, or who see it as part of the 'package'. Thy offer no alternatives or compensation if the bus is out of action for any reason.
It appeared on a number of occasions that there are a lot of things that happen that are beyond the staff's control. While they tried their best to alleviate issues, it did appear that their hands were tied, possibly by management policy (but that's mere speculation). So don't expect too much if a major issue arises.
They have a number of computers available with free internet access (which came in handy many many times!), as well as a good range of DVD's to choose from.
This place would be good for families and people looking for accommodation for a week or more, with access to your own transport, or who know how to use the bus service - otherwise there are a lot of things that you pay for that you simply don't get time to use, or you could wind up stuck either at the apartments or in the city. Also, due to its location, you feel inclined to be out all day, and then once you get back to the apartment, you don't feel like taking the trek back into town!
If I was to stay in Edinburgh again, I wouldn't stay here. I'd spend a little bit more and stay somewhere more central.