The bedroom desperately needs a thick curtain (not just a blind) over the window, especially as sunrise is at 5.30am in summer!
The first six or so steps on the stairs are incredibly steep, but that's just because it's an old Dutch building.
I was glad not to have a big suitcase, but if I had, I'd have done as a Dutch friend showed me. Her home has an even steeper, much longer, and MUCH scarier set of stairs!! Her tip was: always make sure that your suitcase is BELOW you (whether you're walking up or down the stairs). That way you can drop it in an emergency without it falling on you. Just make sure no-one else is on the stairs too, though!
The location is perfect! It's just a 10 minute walk from the central train station, and five minutes to a well-stocked Albert Heijn supermarket. There are cafes and shops a block away on Korte Poten and the Plein; and lovely museums like the Mauritshaus (a must-see) and Escher in Het Paleis (plus lots of other, littler ones) are all a very easy walk away. There's also a nice market (esp. if you're into antique jewellery) outside Het Paleis. There's also an excellent specialty beer shop directly opposite (NB it's not a bar, it closes at 6pm, so noise isn't a problem at all).
Of the apartment itself, it's got a good little kitchen (the main light is over the door -- took me a while to find it!), and lots of space. Very comfy. Gas stove and hot water system.
The owner is really helpful and welcoming (lives just downstairs), but unobtrusive. He cheerily popped up immediately I asked him to check something, even though it was 11pm. While you have to be sure to clean the flat before you leave (or pay a 75 euro cleaning fee), that's standard for these sorts of apartments. It's the usual request to tidy up, i.e. to vacuum the floor, wipe down the benches and tables, leave used sheets and towels in the laundry basket, and report any breakages/problems. Not a big deal, and just what you'd do if you'd been staying in a friend's flat.
Internet access is quick and easy. Overall, I was delighted with my apartment (I had the 'white' one on the 2nd floor), and would love to return.