That does look like a great start. Let me see what other info I can provide.
The basic benefits are functional immortality, excepting something truly catastrophic, like being blown up with your starfighter. The thing provides immunity from disease, poisons, even aging—in the words of the character in question, it just treats old age like any other disease. It provides regeneration, able to bring you back from the brink of death within, say, a week, healing wounds within a matter of hours. It even restores things like pulled wisdom teeth, which suggests it could do the same for limbs and such, given time.
The main downsides are that it requires energy to power it, and if you don't give it some, it will gradually begin to "eat," the host body for sustenance until it eventually kills both. he other main character has to feed his companion cans upon cans of soup, stew, etc, which it somehow can metabolize even while the host is otherwise unaware.
The host in question also has superb reflexes and high-tech gear, but that isn't directly related to her symbiote as such.