I was debating whether to give this a one-star or two-star. I ended up opting for two stars just because the drinks are still consistent with the other branches.
The reason for the bad review was the waitress service here was significantly worse than the other two branches. The layout of of the restaurant is very cramped, and the place we were sitting at is not within the regular field of view for the waitress staff.
Compare this to the Warden/Steeles and Midland branches, the cashier/waitress area can have a pretty open field of view for the entire restaurant, so unless it is really busy they don't have to keep their heads up.
It also felt more cramped, the Warden/Steeles branch is also a bit cramped but still you can move around, this place was just more stifling.
I likely won't go to this branch of Green Grotto by choice in the future. However, I'd still recommend the other two branches.
Also one tip for anyone who does go to GG. ALWAYS ask for sugar on the side (don't bother with reduced sugar). Though most of the drink is consistent, the amount of sugar they put in tends to ruin the drink and some of their drinks ingredients like Longan, Hibiscus and Ginger are preserved in sugar solution so there's no need for them to make it sweeter.