During my stays at Koh Tao, there are a couple of places where I hang out a lot and the Safety Stop is definitely one of them. It's located directly opposite the Sea Lodge, the place I usually stay at when on Koh Tao, so it's also very conveniently located for me.
It's smack downtown Mae Haad, which is also convenient and they serve a nice range of pub food. Free Wi-fi comes in handy and in the evening a lot of divers hang out here.
Once on Koh Tao, a place to visit and enjoy a couple of cold drinks at and possibly a bite. Enjoy it.