NAU is a hidden gem. Most people don't generally view NAU as a highly regarded academic institution; however, the school's small class sizes really give students the opportunity to ask questions and develop personal relationships with their professors. The instructors themselves are passionate about their fields. The salaries at NAU are not very high, so it's more likely that your teachers really enjoy what they do and aren't just here because it allows them to buy a Beamer.
Aside from that, there is a definite culture at NAU that you'll either like or you won't. This applies in almost every area, including academics. The classes are not the most challenging you will find, but the pride of NAU is undergraduate education. NAU does have the highest standards of the three Arizona universities for admissions, but that is coming from the 49th-ranked public education system in the country. The TAs in most programs are another bright spot, as are the free Supplemental Instructors in most programs. TAs generally will take the time to help you study or do better on an assignment you've had trouble with. The education you receive is rewarding; it just takes time to get deeper into the upper-level courses. NAU began as a teacher's college, and while the education program is still near the top of its programs, the College of Business has been flooded with funding the past few years, leading to the building of a state-of-the-art business building. The hotel and restaurant management and forestry programs don't attract as many students but are regionally seen as near the top in their fields. The School of Communication also houses many majors, and you'll have at least one class there during your time at NAU. In short, NAU has carved out a niche as an undergraduate-focused university in a state where that is definitely unique.