I tip 15% for normal service, 10% if below standard and 20% for awesome service.
Went to the Keg last night, no water offered, had to ask for cutlery & share plates.. had 3 different servers in the hour or so we were there. The first guy even brought the bottle of wine out only to realize we didn't have wine glasses either.
They were not very well organized and normally the service (at least in South Surrey) is pretty decent. I was about to leave 10% until my prime rib came out. It was cooked so perfectly and was so delicious that I forgave the service faults and still left 15%