I thought that the grammar and kanji I had to learn for N3 was 100% stuff I use everyday. N2 had a mix of useful conversational stuff along with written grammar rarely used in conversation. I mean, N2 is really important for a lot of reasons but N3 is really helpful to your everyday life if you study for it, I think. Anyone around that level should definitely consider studying for it to help you get your fill of useful grammar.