Wero is based on the Dutch IDEAL system. Because the Dutch already have a good system, they are not joining right away, but at a later time.
The IDEAL system is a replacement for online C2B payments. Rather than entering an incredibly insecure credit card number, the storefront redirects you to your bank, where you safely log in, confirm payment, and get redirected back to the store. It's essentially OAuth for payment. The only annoying part is having to manually select your bank, but even that is now a non-issue with a single unified QR code you can scan in any mobile banking app.
On the other hand, https://wero-wallet.eu/ tells me that Wero is a C2C system, so basically an alternative to Paypal, Venmo, Tikkie, or all the bank-initiated payment request implementations we've seen pop up over the last few years. You can send and receive money via your mobile phone number. So how is this supposed to be like IDEAL?
Reading the FAQs it feels like nothing more than a strictly-worse version of Tikkie, but potentially with an added attack vector for your bank account. In other words, I see very little reason to switch to it.