I've always had great service here. Not sure if other customers were just having bad days and blame it on the help. Vanilla beanfrapp with chocolate chips is fab. Tastes like choc chip ice-cream.
Not the best customer service but for Madison Avenue it is not horrible. If you're in a hurry though the Dunking Donuts a block away is much quicker and friendlier staff.
Terrible Starbucks. They're so slow! And a little rude. Closest one to Mt. Sinai though, but if you're just looking for coffee, go to the Dunkin Donuts on the next block.