We were there on Saturday, around 10pm, and were delighted to be seated without any booking. The only seats were in the backroom - usually I hate backrooms, you are far from the action, they are uncomfi, waiters forget about you, but the backroom at Tender is just fine with nice lounge style seats. So no reason to complain.
The cocktails were all tasty, some very good. And we sampled 6-7 this evening. They also have some punch - beware headaches next morning.
The main room is beautiful, and the bar gorgeous. The service was ok, but not fantastic.
It's not cheap, but the cocktails are worth it.