I've done NaNoWriMo for... a lot of years. (Goes to check -- thirteen years, apparently. Dear god. That long?!)
In that time, I've "won" three times. And I've learned that, ultimately, it's about the journey. It's not a great challenge to do if both of these things apply to you: 1) you have a normal person's amount of free time on your hands, and 2) you want to write something that's good. (You could probably use it to write something good if you had a lot of free time, though.)
If you're juggling school or work on top of NaNo, you'll probably end up writing something rushed and all over the place, even if you do hit 50k words. And that's okay! It's about the experience, it's about the creativity, it's about the community. It's about the journey.
What I tend to do now, though, is to "rebel" -- that is, dedicate the month to writing of some sort, even if I'm not trying to hit the wordcount. I've used it to revise books before (the book I'm currently posting on Tapas, in fact!), and I've used it to sketch outlines and to write the first few chapters of new projects. It can be nice to do that sort of thing with a ready-made community about you.
Also, the forums are really good and really fun. Definitely recommend.