Here is my take on the difference between normal hearing and the CI:
The sound is different to normal hearing, it is a bit more robotic. There are still difficulties with background noise. Hearing people might be able to hear conversations across the room.. I can't, people need to be fairly close to me so I can hear.
I can talk on the phone, so I don't need to lipread. I can hear sounds like sand falling on floors, but sometimes need to ask what it is if I don't recognise it.
I prefer having subtitles for movies and TV, usually because the background has music. But that is my preference, I know some CI users who manage without it.
I make it sound awful, I've just listed all the drawbacks!
BUT - the CI gives enough dB that speech can be understood without lipreading and that is such a blessing.
It gave me a confidence that I had lacked, I am now sure of myself that I have heard something right and can join in group conversations better, rather than hanging back wondering if I've heard correctly and looking like a dickhead if I'm not on the same subject.
There are a lot of sounds (like computer beeping, doorbells) that I can hear again and little things like that make the CI all worth it.
It is definitely one of the best decisions I have ever made to get implanted, being late-deafened in in an oral family, it has improved my quality of life immeasurably!
There is a wonderful webpage which shows hearing people what it sounds like to a CI recipient: http://www.pbs.org/saf/1205/features/Interactive/intro1.htm
So, saying all this and saying how great the CI is, I would recommend it to people, especially to people in "hearing" families but I'm not going to scorn people that don't want one, it is a very personal decision afterall!!