It occludes dentinal tubules, helping reduce dentin hypersensitivity. It's a tooth-desensitizing agent helping people who are for example, very sensitive to very cold/hot temperature in their mouth.

There is evidence that it can foster enamel/dentin mineral gain, but head to head studies shows that it's comparable to regular fluoride toothpaste and not superior. E.g. In a randomized in-situ trial (Caries Research, 2017), adding 5% NovaMin to a 927-ppm SMFP toothpaste did not improve remineralization outcomes vs the same fluoride formula without NovaMin.

Also, you can find NovaMin in the US (e.g., NUPRO Sensodyne Prophylaxis Paste with NovaMin).

I don't know if this is everyone's experience, but you get a distinct feeling of smoothness after using it, unlike any other toothpaste. Since NovaMin reacts with saliva to remineralize the tooth you'd imagine it's a stronger bond than directly filling up crevices with nanohydroxyapatite, and studies seem to [slightly] confirm that.

anecdotal experience: my wife had somewhat botched dental filling proceedure. it probably damaged her teeth in some way and it became very sensitive for any fluids or foods. they tried to redo it, but it only increased sensitivity further.

i gave her apagard renamel (with nanohydroxyapatite ). after a few days sensitivity went down and after a few weeks it completely disappeared