It works somewhat, but I cannot use it on a daily basis so don’t buy it anymore. It causes a reaction with the skin inside of my mouth. Doesn’t make it raw or anything, but it’s just unpleasant.

Whitening toothpaste can appear to whiten teeth slightly by removing surface stains, such as those caused by drinking coffee or smoking. However, whitening toothpastes can't change the natural color of your teeth or lighten a stain that goes deeper than a tooth's surface. https://www.mayoclinic.org/healthy-lifestyle/adult-health/expert-answers/whitening-toothpaste/faq-20058411
You'll have better and faster results using something like Crest Whitestrips.

Very few of my teeth have not been repaired in some way. I also have several crowns and a bridge. I think they'd all turn different shades of 'white'. (No fluoride in the water when I was young.)

Better look at the ingredients of that toothpaste. Many now contain fluoride, triclosan and artificial sugars. I use either all natural toothpaste or just go with baking soda. All my checkups (every 6 months) end with congratulations on how clean and plaque free my teeth are.

Triclosan can contribute to mouth ulcers if you're prone to them, but what's wrong with fluoride?

When I used one of those whitening toothpastes (I think the active ingredient was some version of sodium phosphate--very reactive), the skin in my mouth peeled off. Tried a couple more times with the same effect.

I use Colgate Optic White. I notice a slight difference, nothing dramatic.

Matthias, exactly what happened to me. It wasn't irritating to my mouth, but I definitely noticed it.

Learn some about the issues with fluoride:

http://fluoridealert.org/articles/50-reasons/