Just purchased after using the 30-day free trial, it seems to do a good job. The further 15% comes from Duade Paton's video here https://www.youtube.com/watch?v=2uHaPn9DBXE, the video is pretty informative too and worth watching.
Not sure how much longer the deal is on for, on my browser it says "Hurry! Sale ends in…" then ….blank.
Other Topaz products are discounted too if you check out the Topaz Labs site but as far as I can tell Denoise AI is the one most recommended.
edit: left 1 character out of the youtube link, fixed
edit 3: added price in USD
Mod: personal affiliate links are not allowed on Deal posts.