There aren't very many nice restaurants in the upper part of Washington/Hudson Heights, and Bleu reigns as one of the only options. It's the default when friends or family make the trek up to the northern end of NYC (aka the "Siberia of Manhattan"), just because it's not a diner, not too spicy or weird (ah, unadventurous relatives), has alcohol and a menu that satisfies both carnivores and vegetarians. Is it great food? Nah, but I've never had anything that wasn't decent. Is it a bit overpriced? Sure, but they can do what they like until they get some neighborhood restaurant competition. They do a nice brunch -- who can argue with mimosas and berry pancakes?
As far as the ambiance, it's a strange little place -- lots of velvet and old wood, some odd art, some crystals and swirls, etc. Kinda faux Euro, but none of it is taken seriously enough to be pretentious (which would be silly considering the location). As far as I can tell, it's mostly locals (regulars and people like me taking their visitors out) -- no tourists or scene kids in Siberia, really. Once I was there for dinner and Ron Perlman (Hellboy, City of Lost Children) was at the next table -- his mother lives in the neighborhood and was taking her family out.
Overall, it's a staple neighborhood restaurant that nicely fits the bill when you need something decent that will please a variety of people.