I switched manually last month and as long as you keep an eye on both old and new accounts, it's quite easy to switch yourself.
First I looked at all my sources of income. I changed my account for my salary and changed my account at the Belastingdienst (when you have a voorlopige teruggaaf or toeslagen).
Once these were set and effective, I transferred almost all funds on my old account to my bunq account. Be sure to leave some money on your old account!
I took a look at my expenses in my old bank app. One by one I went to the sites of the companies I gave direct debit authorisation to (machtiging automatische incasso) and checked how to change my account number there.
On most web sites I could change my account number myself, either with or without logging on with my DigID. Some companies wanted me to call them, so I did.
Now I'm in the final phase: I'm monitoring my old account fir any direct debits that still occur on my old account. I have left some money on there to secure that direct debits could be made. Every time I see a direct debit I contact that company to change my account number.
It's also a good moment to clean out direct debits that you don't want no more by canceling subscriptions or donations to charities you no longer want to support.
In a few months I will cancel my accounts at my old bank as I don't have any need for them. I do realise I pay double costs for both bunq and my old bank, but it's only a few euros so I'll take that inconvenience for the full control I now have.
Maybe I will use the Overstapservice in the end, but I want to get rid of old subscriptions and donations I no longer want. The Overstapservice will just transfer them to bunq, which I don't want.
My advise: take the effort and take back full control of your money!