Short answer: very.
Longer answer: They launched 4 satellites bringing the total in orbit to 22, they will need 4 more satellites to complete the constellation. (useless trivia, the launch was the 82nd consecutive successful launch for Ariane 5).
In terms of the geek in the street, if you have a device which works with Galileo, then it will give you better accuracy (approximately CEP of 1m). As for devices, well the Wahoo Elemnt Bolt I just bought has Galileo support built in already, and given that most devices just use an off the shelf chipset from the likes of broadcomm et al, I would expect this to be the norm for many devices. If the EU really wanted to get wide spread adoption, they could do what Russia did. Russia imposed a $25 import duty on all GPS devices that did not support GLONASS (The russian version of GPS). Now everything from your iphone to an eTrex supports Glonass.
So go check what your device supports, look forward to the launch of the final 4 needed for a full constellation (Q3 2018 current schedule). There will be further launches of another 8 satellites, which I think will be in orbit spares, they are scheduled for 2020, 2021 and 2022+.
Bring on EU's own accurate Global Positioning System!
J