The two book system isn't "bad," necessarily. Studying with the main, all-Japanese textbook will force you to figure things out through context and use your brain a little more.
If you're a complete beginner, Minna no Nihongo will present a significant challenge: it's all in Japanese. And we don't mean "there's no romaji," the entire book is in Japanese. You need a separate "translation book" in English to study properly.
The two book system isn't "bad," necessarily. Studying with the main, all-Japanese textbook will force you to figure things out through context and use your brain a little more. You can always check the translation book for grammar explanations when you get stuck.
Minna no Nihongo is very in-depth too. It covers a lot of material and uses complex terms to teach grammar points. It even explains pitch accents with new grammar you learn! This is great because pitch accent should be learned early but few textbooks cover it.
Upon completing the first Minna no Nihongo, you'll know more than if you'd studied Genki I. If you're more academic and want to learn as much as possible, this is a great option for you because you can take your time and soak in the knowledge. If you hit a roadblock, a tutor or language partner would work well with this textbook.