We had a great holiday staying in the apartment over their home. They are both so helpful from collecting us from the station on the first day to the homemade bread on arrival and the gift of chocolate on departure. Hans even called us one evening because we were rather late back and he was worried about us.
If you want a peaceful setting away from the town with fantastic views then this is the place for you. All you can hear are the grasshoppers and the nearby stream. It is well placed for hiking and the buses and trains all run to time so it is easy to plan your day. We hadn't hired a car and really didn't need one. Instead we bought a half price rail voucher each which worked on cable cars as well. Having said that we did find the walk back up to the chalet from the bus stop a little tiring after a busy day hiking! If you want to dine out in Grindelwald in the evening then it is about a 45min walk back (as the buses stop at 18.44) or a taxi ride. We just self-catered.
We would wholehearted recommend staying in this apartment and indeed would stay again if we come back to Grindelwald.