I use them religiously as part of a deal my work has with them but I wouldn't go out the way just to find one. Still/Sparkling water to pour into a glass, coffee machine with tea bags with proper cups, photocopier machine, wifi and you may find a small bowl of hard boiled sweets on reception.
Sometimes I have chosen a Starbucks or the hotel room over a business lounge when I just couldn't be bothered. It's mainly full of people working all day or just touching down for a hour or so, rarely do you see a casual person just using it as a "waiting lounge" so to speak. YMMV.
EDIT: Forgot to add, if they have one of them mini grey water coolers let the water run for a second or 2 if you want chilled as it tastes funny at first (doesn't apply for the room temp option).