As two adults, the apartment was perfect for us. We did not use the loft, so I cannot comment on that. The apartment's location is great - in close proximity to major tourist destinations in Prague, and those that are not that close, are easily reached via public transportation 2-3 minutes away from the apartment. As someone who is sensitive to noise, I appreciated how much the apartment was very quiet. It served us as a great base from which to explore this beautiful city.
The apartment is located in a small and quiet street, but you'll be a minute away from all the hustle and bustle of the city. Either direction you take, you'll bump into some major tourist attraction, shopping, restaurant and so on and so forth. There's a big Tesco nearby for groceries.
As previous reviewers mentioned, it is located on the top, fifth floor. It does take 118 spiral stairs to get up to the apartment. I'm a very fit man, and I confess that I thought twice before considering going up again once I was out. That being said, it's a great way to keep in shape. It wasn't a big issue for me, but it might be difficult to some, especially with a suitcase.