One of the biggest plus points for "Speed Mechanics for Lead Guitar" is that rather than make you sound like a shred-a-like guitarist, Troy Stetina settles for the bare bones of the excercises. The idea, rather than to develop a good set of licks and runs, is to just improve dexterity, finger independance and fluidity. What you do with it afterwards is your own business.
A small criticism, which cannot be helped, is that despite the wealth of genres out there which employ or require speedy guitar playing (jazz, and fusion, for instance), the book draws mostly from metal. While this is not in itself totally bad, the book does need to be updated to at least cite examples from more recent times. Many of the bands he takes his excercises from (Such as Dokken, Ratt etc.) are mostly unheard of nowadays. Also, another small criticism is that it is an obvious direct port over from tape to CD, without updating, and some of the original audio has been lost. This is a shame, as it would have benefitted more from having each excercise audible to the student as a point of reference, rather than having them work out something that ultimately may come out wrong.
Saying that, though - Speed Mechanics for lead Guitar is a no-frills, 'progress in your own time', sensible workbook for the aspiring lead guitarist, and does work through at a sensible and articulate pace.