I applied for accommodation through the UAC, and ended up living at Pax. I was very happy with the arrangements, although I found it quite stressful going through the application process and waiting to find out whether I was successful. It would be good to find out more than 2 months before the arrival date because this doesn't give much time to organise other options, especially if you are travelling prior to arriving in Stockholm, or have already booked flights that don't allow you to come earlier to make arrangements.
The standard and cost of the housing was acceptable to me as short-term student accommodation. However, I was very disappointed by the quality of the mattresses and also the curtains - the mattresses are like camping beds, and the curtains are useless, which is especially annoying given how long it is light outside now!
I also think it would be good to provide more information about the housing on arrival - I was very confused at first as to how it all worked with the shared kitchens, cleaning, laundry etc. It would be nice, and a lot more welcoming, to have this information included when you pick up your keys.
Finally, while I did not live on an exclusively Karolinska corridor, I think this is a really good idea. It is obvious that the KI students stick together anyway, and are also often here for shorter periods, so it makes sense to all live together on the same corridors.