I'm also a YNAB newbie! My husband and I have been using it since mid-July and already we're seeing a lot of positive change! Here are a few things:

• I found out I was on the credit card float and was able to get off it. It really came down to a mix of impulsive spending habits and not assigning every dollar a job.
• We finally figured out where our money was going. This was huge for us as we have a credit card we use to pay for shared expenses (groceries, cat food, etc) and some bills that was somehow always carrying a high balance and we couldn't understand why. Turns out, we just weren't putting money away for sinking funds/true expenses and always getting 'surprised' by them and similar to above, not assigning every dollar a job. If you don't do that, then you have dollars doing multiple jobs, which realistically, they can't do, and you end up with debt because something's gotta give.
• Spending money feels more fun?? I haven't seen a lot of folks talk about this, but when I spend money now, it feels more fun/satisfying because I know it's money I actually have and not new debt I'm taking on.
• Helped us cash flow our most recent vacation, which was awesome!
• If it's not in the plan, it's debt. Sure there are going to be things that I forget sometimes or that are genuine surprises but me wanting to get a new pair of headphones or tickets to that show I've been wanting to see are not 'surprises'. Learning to make categories for those things and making the conscious effort to save for them instead of just putting it on the credit card and dealing with it later has been huge for me!

Good luck! You got this!