I'm from the UK, I didn't get onto the web until 1999, before that we used Teletext. I think the advantage to it was most televisions supported Teletext by the 1980s and it was a free service - albeit you had to pay your annual TV license.
The white/yellow page service (3611) was free for the first three minutes and was widely used. My parents never had the (huge) yearly book version at home.
As mentioned in other comments it was also widely used to consult Baccalauréat (national exam like SAT) results.
3611 used to offer the first 3 minutes free for a few years then removed this.
There were no services available for free, at first there were two kinds: the service provider pays the operator or the user pays the operator (about 3€ an hour). no money for the service provider. Then came the kiosk offer which started the golden age: the user now pays 9€ an hour with 6€ for the service and 3 for the operator.
After few years everybody I know had one per household, except for my grandparents. Pretty much every household who wanted one could get one.
Later they built more fancy terminals (faster modem, combined with phone, better screen/graphics, etc.) and rented them. The free one was still a good deal.
The White Pages where totally free. And if I recall the Yellow Pages had a the first minute or so free. I remember navigating the pages as fast as possible to not pay the fee.
As mentioned before some school results and even applications were made using the terminal, for residual fee on the phone bill.
My mom was buying online (3Suisses, Redoute and CAMIF) through the terminal from early 80's until early 2000. She had a hard time to move to internet website when it comes to buy online. She heard so much of CC fraud online that she felt safer using the Minitel.