I think it sort of depends on what you're looking for from a frugality book. TG is one of the first books I read when I was in grad school and had just figured out that having my dream job was going to mean a frugal lifestyle pretty much indefinitely. What made it stand out at the time was that it was unusual in mixing articles about the theory of frugality, general principles that could be applied in multiple situations (like how to make muffins no matter what ingredients you had around), and then very specific tips. At the time, pretty much everything out there on saving money consisted of lists of tips without a whole lot of context. She did some case studies "dishwashing vs. hand-washing" but was clear that she meant them as an example as to how people could analyze their own situations rather than a rule to follow.
I haven't reread it for a number of years, but a lot of her "theory" articles have stuck with me--the ones about how to figure out whether the more expensive choice is worth it, what we owe to people who make poor financial choices, how she and her husband decided to divide up the household work, the idea of "creative deprivation" (by which she meant, limiting indulgences so treats are really treats). Amy D's gift was that she was able to put some concepts that would seem very off-putting or complex into everyday language or share a new perspective--she did cover some of the same topics as MMM but I find her style much more appealing.
A lot of the specifics would be very dated now. She was living in rural Maine before the internet took off, so her methods of shopping, etc. might not make a lot of sense now, esp to those of us in cities. She retired because she felt she had covered all the material worth writing about...and of course that was not long before the internet/mobile technology changed a lot of the rules and options. Wish she had kept at it...
So...overall, worth dipping in to? Considering that used copies are available for $4.50 on Amazon, I think it would be worthwhile purchase since the book can be regifted or donated if it doesn't suit.