If you don't have Denoise projects yet, assuming you edit images, this is probably worth getting.
I bought Denoise projects Pro 2 -- I'm still undecided about their new Pro 3 -- and use it quite a bit via P/Shop. Using it that way is a little bit slow, waiting for the app to open and analyze the photo, but keeps the results on a layer I can modify or discard. While it works [or obviously I wouldn't use it], at default settings the results are not nearly as dramatic as the images on their product pages suggest. While I can amp up the settings, doing so usually has side effects elsewhere.
To describe the results I get, I need to start with the basics... Camera sensors, & the pattern [grain] of chemicals deposited on film negatives & prints, vary in sharpness. As you zoom in on a photo in an image editor, the less sharp the image the more you can see blobs of colored pixels. With some cameras the colors of those blobs is far from uniform, achieving colors by blending rather than showing the true colors more naturally -- same as how a printer works to print green by blending blue and yellow. At any rate, using Denoise projects doesn't eliminate those blobs -- doing so would make the photo even less sharp -- but it does consolidate them, making the tiniest blobs & stray pixels match their larger neighbors.
It does help the overall appearance of many photos -- it helps most all of our old prints I'm scanning -- but Franzis' advertising exaggerates to put it politely. You are not going to get the same results as a mid to high range Canon or Nikon or Sony camera unless you use one of those Canon or Nikon or Sony cameras. You can't unblend pixels any more than you can unblend a drink. ;)