Does it hold the can by itself while it cuts?
Yes. Once the can is seated and you have pressed the lever, the opener grips the rim and turns the can hands-free until it stops automatically. If you expected to have to hold the can, you will find you don't need to.
It starts and then slips or stalls partway round the can. What is wrong?
Usually food residue rather than a dying motor. The blade passes through whatever it opens, so brine, oil, syrup and tomato end up on it and between the gear teeth, where they dry hard and stop the gear biting. Wash the removable activation lever after messy cans, and never immerse the body, which houses the motor. The other common cause is a dented can: the gear tracks along the rim, so a distorted rim derails it, and forcing the machine is what damages the gear.
How do I stop it walking around on the counter?
Check it is on a clean, dry, flat surface, since the extra-wide non-slip base is what keeps it planted while the gear turns the can. If it still moves, the base or the counter may be greasy, so wipe both down. It is designed to be used without steadying it, so if you find yourself holding it still, the surface needs attention.
Is a manual opener actually better?
Only if hand strength and grip are not a concern. Opening a can by hand needs a firm grip with one hand while turning a key with the other, which is one of the first everyday kitchen tasks to get hard with arthritis, after a stroke, with a tremor or with age. For an able-bodied household buying purely for convenience, a manual opener needs no socket and has nothing electric to fail.
Is it a good gift for an elderly relative?
Yes, it is the buyer Cuisinart designs it for. Test it yourself on a few cans before giving it and keep the receipt. The person most likely to need this kind of device is also the person least likely to pursue a return if it turns out to be faulty, so doing that legwork on their behalf is worth the few minutes.
What size cans does it handle?
Cuisinart says it opens any standard-size can and describes it as working with cans of various sizes. If you regularly open unusually tall or catering-size cans, check the height of your own cans against the opener, which stands about 9.35 inches tall, before relying on it.