Food is delicious, some of the best anywhere on Disney property.
Atmosphere is nice, but there have been numerous children whenever we have dined there. It is very noisy in the reception area with people running in asking if they take the dining plan since it's an hour wait at Chefs even with an ADR. It's better upstairs but we have certainly encountered noisy groups.
The wine list is not very extensive for a restaurant of Bistro's caliber and pricing, and the choices by the glass are very slim pickings. For red last month, they were offering one burgundy, one Cote du Rhone and two Bordeaux -- and they were out of the Cote du Rhone!
The seating is annoying. They will insist on seating a party of 2 at a 2 top rather than a 4 top, even at 8:30 pm with 20 empty 4 tops.
I find the language barrier to be a problem at times. In other words, the waiters' English is not as good as it should be for seamless service without hiccups and misunderstandings. Also, the service is French -- not relaxed and friendly like V&A, much more formal and somewhat supercilious, IMO.
There is no dress code other than the one applicable at all Disney restaurants other than V&A (no tank tops on men, no swimsuits, no offensive t-shirts, no torn jeans, although that one is not really enforced). In other words, park wear, basically.
A friend and I dined at both V&A and Bistro last month. Her take: Next time we're at Disney, she says Bistro was so expensive, she would much rather spring for a bit more, dine a second night at V&A and skip Bistro.