It's not isolated.
If you earth the terminal marked earth, it will trip the ELCB/RCD/GFI and if you don't, the voltage and current on that pin will be enough to kill you. (Ok, less likely to kill you if the supply is 120 V, but it will hurt)
Also, 250 V capacitors on 230 V mains, is asking for problems. And there is no inrush protection.
The page you linked to is written by another armchair idiot, who has obviously never made the circuits and touched the output. (Well, if he has done so since writing the article, he won't be writing any more)