As someone who has had cochlear implant surgery myself, that is 100% true. Luckily as a member of the Deaf community I knew full well what to expect so I didn't expect to hear straight away and just looked forward to taking my time learning how to hear. Even now I still can't hear 100% (and will never be able to) but that is fine as I still use our national sign language which will always be the language I can communicate best in. It took a bit of adjustment for the hearing members of my family. Even though I kept explaining I won't be able to hear perfectly from day 1, it was still a shock for some who realised the switch on was only the start of an incredibly long journey which I am still on. Ironically, only those who had deep involvement in the Deaf/sign language community understood exactly the reality of cochlear implants -- showing that even with medical advancements, the Deaf community is still an important part of any Deaf person's life and sign language will remain a useful toolkit for all Deaf people.