I would think unless you are a really big fan of GBS you will only spend an hour or so around there. It was a nice afternoon out and lovely to take a picnic, as there are no catering facilities there, just some ice-creams.
The garden is lovely and slopes away from the house, but I did feel that it could do with some attention, particularly the flowerbeds, the orchard and wooded areas are fine. GBS had a writing hut which is still in the garden.
As you can see the house in not a 'stately manor' just a large house with servants quarters.
There are some seats around the grounds and we did take a picnic and enjoyed just sitting in the grounds in the sunshine.
There is a lot of information about GBS in the house and there are volunteers that take you through a lot of the history. If you enjoy the history of the writer there is so much to see, and it is still as he left it.
Parking can be a bit tricky, as the car park is quite small, but there is a steady stream of people coming and going.
As we are National Trust members it didn't cost us anything for the entry, I did think that the entry price was a bit high at the time.