I have never been to the bricks and mortar Granth store, but have been registered with their site for almost 18 months now.
Due to a busy schedule and distance issues, I cannot travel towards town for browsing through books etc. Granth gives me a great way to get my books delivered to me.
The best part is that they also accept Cash on Delivery. This attracted me to Granth in the initial instance because I did not have a credit card when I joined Granth.
They offer good discounts and you can also gift books from their site.
The only area where they seem lacking is the slow delivery time. If I would need something urgently, I would still prefer to go to a book shop and purchase a book quickly, because Granth takes almost 5 days to deliver a book. Any improvements in this would be extremely welcome.