I've been a mac user from 1994 until around 2014 and I decided to give this a go on my old 600MHz iBook (which has been through 2 motherboard replacements in its life since I bought this back in 2002)... and it does seem to make a slight improvement in performance. Honestly it does seem rather hyped up since it's more like a compilation of stuff that people have found many years prior (anyone remember OSXdaily? They documented a couple hacks for leopard years ago) yet I also think he seems to have discovered some new tweaks. I know disabling spotlight has made a noticeable difference, but I'm honestly not sure if a good amount of the tweaks are just placebos or gimmicks. Also, this is tiger on a G3 iBook so it isn't going to be like my PowerBook G4 which absolutely flies on tiger...
I've also installed an SSD (which, by the way, is a pain in the ass!) and maxed out the RAM on here to 640MB. I do notice a speed difference with shuriken applied, but honestly I don't get the whole apple event schtick. I am typing from this right now through AquaWeb Micro, which is resource-intensive on here as I would expect considering this is a 21-year-old laptop.