I'm in no way, shape or form a Berklee student, but I think there's a lot of good things in the three-volume "Modern Guitar Method" by Bill Leavitt, who founded the guitar department at the Boston music school.
I saw some posts in the Yahoo Jazz Guitar group recently recommending Leavitt as a beginning method, and it's there that I pause. Yes, there is plenty in Book 1 that is fundamental, but I think it's better as review for a guitarist getting into jazz from other genres than as a raw introduction for somebody new to the instrument or to music in general.
Somebody on that group said that it would take you until book 6 in the Mel Bay method to get to the same place as book 1 of Leavitt. I might agree with that statement. I came up with the Mel Bay Classic Guitar Method and, to a lesser extent, Mel Bay's Modern Guitar Method (not Leavitt's), and I think there's a lot of value for the beginner in those books. I see the same value in other beginning books (just saw the Hal Leonard method, and that looks good for beginners, too). For one thing, I think Leavitt will scare away beginners. It's just too much of a leap.
That said, for the guitarist coming from a rock and/or classical background (and that's me), Leavitt offers quite a lot in terms of position playing, chord forms, scales and arpeggios, all meted out in graded fashion and all designed to get you reading and playing all over the neck in all keys, major and minor. And there are more books by Leavitt to supplement this material.
I have the three separate volumes, but the Leavitt "Modern Guitar Method" has recently been completely re-set -- it's much, much clearer to read now -- and gathered in a single volume, which I recommend very much.
Now there is some controversy over the Leavitt scale fingerings, which use a lot of stretching by the first and fourth fingers of the left (fretting) hand. The Segovia scales, which I used to be able to play without even looking at the book (it's a thin book, don't worry) favor shifting instead of stretching (and there's only one way to play each scale), and I don't think there's much if any in the CAGED system favored by Joe Pass (see his "Joe Pass Guitar Method," the blue book). Additionally, Jimmy Bruno's "Six Essential Fingerings" book does not use much shifting, and there are few guitarists today that are better than Jimmy, so he should know.
In my analysis, the Leavitt fingerings tend to emphasize note awareness and fingerboard mastery over pattern-playing. As Jack Grassel demonstrates in his book, "Guitar Seeds" there's a PDF of this page on his Web site), the Leavitt system allows one to play in all 12 keys from a single six-fret position.
Berklee has turned out a ton of guitarists over the years, so there are plenty of proponents of this system out there. I think it's up to each individual player to figure out what works for him or her. The main thing is hearing the sounds in your head and then playing them on the instrument. That's the aim of this whole thing -- to learn the jazz language and be able to "speak" it on your instrument.
If you do learn all the major and minor scales, arpeggios and chord forms in the Leavitt books, you have a lot to work with. Improvising, accompaniment, ear training and sight reading will all benefit from this work.