I've worn hearing aids since 1988 or so, I was 34 and fairly hard of hearing.
Nowadays I get mine through the military (not the Veteran's Administration, I despise the VA and will not accept anything from them) as I was diagnosed and issued my first hearing aids while on active duty. This method allows me to buy them at the military cost, just over $300 each last time around. I wear in the ear models, they're small and fairly nice, my current model is Phonak but I've had several Unitron and others. They seem to last about 5 years and die due to bad switches or battery doors.
The commercial hearing aids are custom fit for the persons individual loss, trying to create a sound gain curve that compliments the hearing loss curve resulting in a nice "repair", they don't simply amplify everything as not everything need it.
Most have a compression circuit to protect against accidental exposure to loud noises.
The batteries are very different than most, mine are air activiated so they store nearly forever and when they go dead it's in a matter of seconds. They seem to last about 2 weeks with the only off time being when I'm sleeping.
Tips: Carry/store extra batteries everywhere, in the car, at work, back pack etc. (They go dead "right now" and when that happens you'll be unhappy without a replacement.)
Don't swim with them in your ears, it won't matter if its a planned swim or unplanned, its a bad idea and they don't like it.
Get the replacement insurance for your first few sets, they can get lost or eaten by dogs and cats. (Pets really enjoy the smell and apparently the taste of hearing aids.)
It is very nice to be able to hear well, I really didn't realize how much I was not hearing until I got my first set. I thought crickets had become extinct and I could hear women and children well again, things like 'Who's shoe am I touching?" didn't sound like "Who's chewing my Texan?", and many others.