ATP is a specialized school. It is best suited to those who are highly strapped for time and do not wish to learn in the traditional way. You also need to be highly motivated; meaning, you need to teach yourself a lot of what you need to know. They will not spend a lot of time teaching you academic stuff. The flight training is geared towards what is required by the PTS and nothing else. They are training you towards a checkride with a handpicked examiner.
You stated that your goal is to acquire an Airline Transport Pilot license. Bear in mind that there are many, many minimum requirements that need to be met. ATP will not get you there from scratch, although years down the road many choose to return to ATP to get their ATP license.