I did the same thing. It means YOU personally will not have to deploy for a combat rotation overseas for two years. But you will have to go with your unit if you are called up in the case of a natural disaster or other similar mission.
The National Guard is pretty cool. As a two-time Iraq veteran, myself, it's nice to have a monthly get-together with folks who've deployed overseas. It's only two days a month. But sometimes those two days can be pretty boring. It seems like we spend half our time doing the same mandatory stuff we did on Active Duty - like updating SGLI forms and attending suicide prevention briefings and updating our medical data. Unfortunately, since you only HAVE two days a month, you spend a larger portion of your time with that kind of thing.
Discipline is not as strict as your average Active Duty unit. It's not that people have no military bearing, it's just a little less enforced. (Don't push it though.) Unit quipment is not replaced as often, though you'll probably get new personal gear (web gear and helmet and sleeping bag and so forth.) There's some differences in pay and administration and promotions and TDY training. You'll pick up on that as you go. Don't be afraid to ask!
It can be just as frustrating as Active Duty, as far as tedium and impossible dead lines for inspections and long days at the range and the Good Idea Fairy attacking. (Command staff tends to be less experienced so you get the Goo Idea Fairy coming around more often.)
Overall, it's not bad. The extra little bit of income helps. If you want to do some college courses, you may be able to get tuition assistance. You will be paid full-time pay if you do get a TDY course. And one weekend a month sure beats getting called back out of IRR for another combat rotation!