If this is your style and Dream Theater your fancy then by all means buy this because it will let you see just how devoted you have to be to become this well versed and facile with guitar lore.
John is showing us what worked for him long term after he got the basics down. Experience is what you cant fake.
You will be thrilled to learn that I have made a favorable assessment. My impression right now is that as guitar presentations like these seem to go, Petrucci's Rock Discipline is a very well thought out presentation.
One with its heart in the right place kind of guitar lesson. Its advanced but he gives you a context from which to move forward from the lesson lesson and also a real live, hold in your hand, innovatively bound pamphlet that will lay flat in front of you!
There are scale or linear examples, arpeggiated examples, left hand or legato playing and sweep picking examples.
That above list is what he practices daily depending on time. A little bit of each. This is a glimpse into Mr. Petrucci world & daily routine. He talks about how to build up speed using scale fragments (45:57) and they are in the pamphlet plain as day! A committed, grounded, beginning guitarist could take this guitar knowledge and work with it and improve.
If you can dream it, you can achieve it. – Zig Ziglar