Yep, I use it on a 800MHz G4 and it runs slow. I never expected it to be anything else. All I use it for is to test PC browsers when modifying stuff on PPRuNe and to remind me how cr@p most PC operating systems are!
If he bought it without reading reviews and expects it to blaze along like a real PC then it will be disappointing. If you only want it to run some obscure PC software that doesn't require blindingly fast CPU then it's great.
For most peoples computing requirements of word processor, spreadsheet and internet, you wouldn't need a PC emulator. Almost anything sent to you from a PC can be opened in the equivalent Mac program. Had to reload Windoze 98 once.... never again.
What a pain that was.