For us, a group of 4 recently graduated Theatre students who needed somewhere to crash during a long weekend at the fringe, the flat was just about OK.
Highlight was the location - minutes away from the Mile and perfect for the majority of the venues and bars we go to up there. Beds were comfy enough, the whole apartment was relatively clean, kitchen all worked just about, it felt relatively safe and was quiet enough at night. We also found it pretty easy to find, unlike some of the other reviews, and the email instructions of how to get in was simple enough to follow.
But if you are anything other than a group of young people looking for somewhere with a roof to sleep, I'd avoid if I'm honest. Not a relaxing or overly welcoming apartment - and the bathroom was simply not up to scratch, even for us.
There was no lock on the bathroom door, and barely any hot water ever (even when we left it on for a couple of hours to heat up, it filled up about half a bath before going cold again). Water pressure was also a major issue - in order to make any water come out of the shower head, you had to sit in the bath. We ended up 'washing' by sticking our head under lukewarm water in the tap. Expect better than this, really, considering it was cheap - but not 'that' cheap.
All in all, fine for somewhere to crash but I'd feel sorry for any family/etc. if they ended up there and was expecting a relaxing holiday in Edinburgh! Don't think you'll want to spend too much time there.