Had a great stay at Jan and Sarah's place on my first visit to Prague. Great location - easy walking distance to Old Town and many great restaurants, bake shops, pubs, etc. Jan and Sarah provided a great list of recommended restaurants - I tried several and all were excellent.
They were also very responsive to any questions I had which was very helpful.
Finally, I got a chance to meet them at Hotel Nerudova (super nice boutique hotel they recently opened) and we enjoyed a nice chat over coffee. I recommend stopping by on your way to or from Prague Castle.