I stayed here for 3 weeks with two small kids (2 and 4 years old) and it was a perfect place with good access to public transportation. The bus was a 2 minute walk from the flat and the train station was either a 9 min bus ride or a 20 min walk. It was usually about a 0:45-1:00 ride into Edinburgh via bus (during festival season). The views are fantastic and there is almost everything you need within walking distance in this town. The host's house guide lists the local grocery store as a convenience store, but I found it more than that with everything I needed from fruits, veggies, meats, cooking supplies, beer/wine, and don't recommend walking to the larger Tesco.
Ben was quick to answer any questions I had and the neighbors that I met were all super friendly. The food, bakeries,/coffee shops, and pubs in town are great, particularly the ones that Ben recommended. I have to say that in three weeks I think I tried almost all of them.
I never found a playground close for small kids, but there are plenty of safe places for them to play, particularly some of the walking trails and the pedestrian bridge. The kitchen is more than adequate and the living areas spacious for Europe but I found the shower a bit hard to take care of the littles. Doable, but It is quite small.
I highly recommend this stay and really hope that my family can return for holiday in the future.