Don't worry, WPS will just pull your router's wireless settings (ie. the WPA passphrase) into your WiFi-enabled printer. :-)
The bad news is that WPS comes with several methods (the push-button method + a few other methods) including one that has recently been completely broken. So if you don't deactivate the WPS functionality on your router, your network can be hacked in just a few hours of brute force attack.
So here's my advice: use WPS (the push-button method) to configure your printer, then immediately deactivate WPS on your router and only activate it when you need it.