G220's are a dual action polisher mate, meaning it does not rotate one way, meaning it takes longer to work with. these are good for people who have not used a machine polisher before as it is very hard to burn through the laquer with, so ideal for a beginner.
I have a kestrel DAS-6 which is similar and a bit cheaper and basically does the same job, only thing with it is i dont think you get a good level of correction with as you would with a rotary polisher.
They bring the paint up nice and give a good shine but when it comes to damaged paint with swirls or light scratches i dont think they do much with them.
I peronally think they are good for putting polish on and minor correction.
For polish try Poorboys black hole which works really well on blue and dark cars.