Tae Kim's guide is very complete in terms of modern grammar. Of course it doesn't include the entire language's vocabulary and doesn't really address learning kanji at all, although it uses them. It also only touches on antiquated grammar here and there, in cases that are likely to still appear, if only rarely, in modern usage.
The guide has two disadvantages however, one of which is the lack of comprehensive dialogues (for comprehension practice) and exercises (for production practice). The 'complete' guide remedies this somewhat compared to the 'grammar' guide, but it still is inferior in this respect to the better textbook courses.
More importantly for you, I think, is that it has a very idiosyncratic way of explaining things. In particular, it uses a lot of highly ungrammatical pseudo-English to give very literal translations of example sentences. This is fine for native speakers who will immediately recognize that the expressions which are ungrammatical in English help demonstrate the Japanese grammar... but for the non-native speaker, I expect this creates an enormous barrier to understanding. Of course, the guide has been translated into many other languages (I assume it uses similarly ungrammatical examples in those translations, though I can't read them myself to check.) If your native language is one of those, then that's great... but if you're trying to use Tae Kim in a version that is not your native language, I don't think it will be very easy to understand.
