well, I have never took class there, but i have two friends who have.
Actress Friend #1 - She studied at Atlantic Acting School as part of her NYU Theatrical program. The technique works for her, and she has done numerous of films - I had the chance to work with her on two short films, and she's very committed to the role, and very natural on screen. Directors loved her performance.
Actress Friend #2 - She studied at another acting school before she decided to join the 2 years program at Atlantic. To my surprise, after the first year, she decided to end the program. She told me, the technique just doesn't work for her. (This particular is one of the REALLY Good actress that I've ever met - so I was surprised with what she told me).
In terms of reputation, yeah, pretty good. When I ask my manager what schools she would recommand me to continue training, Atlantic was one of the names she mentioned.
But if you want a school that has a lot of weight in the industry... I'd suggest William Esper Studio. (Of course, also Julliard, Lee Strasberg, Neighborhood Playhouse, etc)