I have to admit the shine has worn off a bit and I do play catch up some months, especially on DH's CC as it has a weird quirk that you can only access the statement once a month, so if he spends money without telling me then I don't always realise.
But all in all it's still well worth it. I've just had a baby so our finances are taking a bit of a hit but we're nowhere near the low of where we started out.
Catching up with the thread a bit...
I have debts on mine - we had three loans, two of which are now paid off. I put them in as a "tracking" account so I can see them but they don't tank my actual budget. I also put the full limit of the overdrafts in as "tracking" and use the "available" number from my bank as the balance, but for example for a €5k overdraft, I then immediately "paid off" €2k of that that I didn't want to access. I find this is better than having a bank account with a negative number that YNAB doesn't understand (because bank accounts in America don't work that way, I think). I budget for the overdraft fees/interest separately so that isn't just increasing constantly. This gives me a clear "floor" that I know that account can't go beneath.
The first half of the first year is really tough because you'll have a load of true expenses that you'd normally have a whole year to budget for but you need to fund within a few months. Also because of their CC management system if you've been paying off the credit card with next month's salary then you are essentially double paying this on month one, as you have to pay the previous month's bill but also withhold anything you spend on the card this month.
Would highly recommend the Chrome extension "Toolkit for YNAB" if you use the desktop/web version. It gives you more reports and some other useful options.
You can put in your bills/direct debits as transactions with a future date, and tick the box underneath saying "Repeat weekly/monthly/etc" - I find this better than targets. I don't use the weekly target at all actually, I just put in a dummy transaction for the weekly shop with an estimated amount. It has the same effect for "underfunded" with some very slight differences that work better for me.