For some of these products, I found my judgement depended quite a lot on how much I actually knew at the time (i.e. how "good" I was).
IOW - it's easy to rate teaching products as bad if they are actually too advanced for you ... because in those products the author is not going to explain everything, and he/she will assume you have considerable knowledge & skill to begin with.
My first example of that is Don Mock's Book on Melodic Minor. When I bought that I was just starting with Melodic Minor, and Don's rather personalised approach just confused me and led me to put the book aside rather too quickly.
Another example is Mick Goodrick's book The Advancing Guitarist.
I've since found Don Mock's Melodic Minor book very helpful indeed. Although I haven't looked much more at the Goodrick offering.
Of course in music books, the authors should clearly explain what level the material is aimed at. But in my experience they rarely explain that in any clear persuasive way (perhaps the publishers think it will harm sales if the author starts by explicitly saying the work is inappropriate for 99% of likely buyers).
But, as I say - in many other cases, the teacher/instructor clearly could not be bothered about his lessons at all, and appears to have dashed the whole thing off in his lunch hour. That seems particularly prevalent with famous name presenters.
Imho, in his instructional DVD/video, Holdsworth clearly puts in no more than 10% of the required effort. And correspondingly I wouldn't rate it more than 1 out of 10. IOW - a complete waste of money.
Paul Gilbert, who was criticised above (I think), is the entire opposite. All his videos and DVD's show terrific commitment and attention to detail. They are certainly amongst the best guitar tutorial products ever produced, and probably far better than you could get from any private teacher no matter how many lessons you had .... but, of course, those products are all very specifically about fast picking "shred" work, and you would not buy those if you wanted applications of theory in jazz-fusion playing.
The older videos produced by Hot Licks are almost all utterly useless! One in particular has a group of famous guitarists totally wasting everyone's time inc. their own! ... Mick Taylor and Nils Lofgren are prime culprits...why they ever bothered turning up I'll never know. A notable exception is the Jimmy Bruno jazz video/DVD, which is very good.
People have said much the same about Malmsteen's original video ... as if he really didn't want to tell you any of his "secrets", in case you learnt to play as well or better than he can! I haven't actually seen that full video though.
At the other end of the scale we have products like Scott Henderson's DVD, which is frankly worth ten times the asking price (literally).
But even with the very best of these tutorial DVD's & books etc., you only get out of them in proportion to the effort and commitment that you put it .... it's easy to extract far less than that, not because the teacher or his material is no good, but because students often expect the product to do all the work, as if they merely need to stick the DVD in the machine and watch the film. But that's no good. Instead you need make it the basis of every day practice and wear the dam thing out!
2:cents (OK it was a bit more long winded than 2-cents, so maybe 4-cents)

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Ian.