I've been in Tokyo now 18 months, took private lessons twice costing about $2,000, and feel I learned 10 words. That's $200/word. I joke with people I stopped taking lessons because learning Kanji would bankrupt me. Japanese just doesn't stick in my older and very Western brain. It doesn't help that my office does business in English and one can get by in Tokyo with minimal Japanese and a lot of pointing and gesturing. The glacial progress becomes discouraging.
I tried Rosetta Stone. It takes the same phrasebook approach as the first textbook I was given, Nihongo Fun & Easy, which was neither. The textbook at least had short sidebar discussions of grammar and somewhat useful phrases. I had no idea where I'd get to use the phrase "The children are swimming," that Rosetta offers.
The 8020 article was the first discussion of particles that actually made sense. When I'd asked teachers about particles before the answer was usually something like "Don't worry about that yet, just memorize the phrases." If the remainder of the book is in the same vein I'd pay twice the asking price. I flipped through parts of Nihongo Fun & Easy after reading this article and it suddenly made much more sense. I wasn't staring at a list of phrases I was supposed to memorize and slowly reverse engineer the language, but could deconstruct the basic sentences.
It's much easier for me to learn construction, and use the break down of other sentences to construct my own, even if the rules fail sometimes and lead me to construct sentences no native speaker would utter. That's the other 80% of language idiosyncrasies that takes time.
I don't expect to be fluent in Japanese any time soon, however moving past "sumimasen kore onegeihshimasu" while pointing at a menu item would be awesome.