In my opinion, the CI is *much* better than a HA! I'm able to hear whispers, female voices, birds singing, communicate in noisy environments -- the list goes on and on. I can also hear at a distance -- something I couldn't do before with HAs.
If truth be told, I hear better now than I ever have before! Prior to my CIs, my speech understanding was 22% for sentences in quiet and 0% for sentences in noise and single words. With a single CI, my speech discrimination improved to 93% for sentences in quiet and 90% for single words. With bilateral CIs, my speech discrimination in quiet was 97%, 95% for sentences in noise and 92% for single words.
Thanks to my CIs, music sounds absolutely wonderful! I can hear all of the layers of music including harmony, melody, background vocals and I can identify instruments whether they are played alone or in unison. With HAs, music enjoyment was a one dimensional experience. With my CIs, it's three dimensional.
As far as the qualifications for a CI are concerned, I've heard of two cases where people with moderately-severe to profound hearing loss were implanted. However, general CI criteria state that a person must have a severe or severe to profound loss with speech discrimination of 60% or less in the better ear and 50% or less in the worse ear (aided).
How well a person hears with a CI varies. Some people are able to talk on the phone while others hear environmental sounds.
There are no guarantees as to how well a person will function with a CI, but hard work, persistence and a positive attitude can go a long way towards ensuring that a person does the very best they can with a CI.