I use it, but I use the old version. I am actually getting ready to migrate to the new version for 2021 though because my ancient Macbook I use the desktop version on is dying. I do really like the system overall and the every dollar principle of budgeting works well for me. The biggest complaint/thing I don't like about the new system is the inability to roll over deficits in a certain category. For example, if we paid for my husband's hotel on our credit card for a work trip in November and he doesn't get reimbursed for it until December, I would roll over the negative balance into next month's category and then fund it once we receive that reimbursement. New YNAB will no longer allow you to do that because it's "not a true picture of your budget" and you should be funding each category in full or not spending the money. Well, I don't need to fund that category because I'm not actually spending my money when I'm getting reimbursed two weeks later

So now you have to manipulate it by going and essentially backdating that reimbursement payment for the previous month's budget. Otherwise, YNAB, will automatically subtract your overage amount from your income in the next month's budget.
I hope that made sense! I do really like the system otherwise.