Hi DanL. My husband was on the generic, donepezil, since 2019. He did not experience any side effects, such as bad dreams or gastrointestinal upset. His neurologist always inquired about side effects. He's prescribed citalopram (low dose is supposed to help with mood, energy) now, so discontinued the donepezil. I don't know if the donepezil did my husband any good. He was holding his own for a while, but his short term memory is worse lately. I also had mixed feelings about donepezil as a newsletter I was getting "Worst Pills, Best Pills News" noted it was one drug never to take. Also, through "Worst Pills" I read about the following:

NEW WARNINGS ON AN ALZHEIMER’S DRUG
February 5, 2015
Here’s an important alert for Alzheimer’s disease patients and their caregivers.
On January 21, 2015, Health Canada, the Canadian equivalent of the Food and Drug Administration (FDA), issued a warning concerning two rare but potentially very serious adverse effects of the drug donepezil (ARICEPT, ARICEPT-23).[1]
Donepezil is approved for the treatment of Alzheimer’s disease. Generic versions are available from more than 20 different companies in the U.S.[2]

I hope this helps.