Are they starting from chapter 1 in the book? How does that compare to the knowledge you already have? Will you be able to continue right away after the first 12 lessons?
I take a Japanese class that uses Minna no Nihongo, and it suits me at least. I am learning from a veey passionate non-native teacher (25 year translator, married to a Kyuushuu woman and raising their kids Japanese). He strongly believes in building a broad foundation in grammar understanding, so it goes slow at the start, but he teaches 6x3h lessons a week at different levels (and you are allowed to go to as many of those for the same 12 week fee, so you can basically go at your own pace). He would never think to skip the listening practice (even adds drama shows to watch in class as you progress to the 2nd book). He also turns the writing exercises into conversation practice, and renshuu b become translation exercises, instead of ‘fill in the correct conjugation’ exercises (Dutch-JP).
With the right teacher Minna no nihongo can take you very far.