If it's pre-mixed, the match is usually pretty good. If they are mixing it in store, it's down to how good the individual is.
I used them, and had Prestige Blue mixed up so I could spray my headlight brows, and it was a shit colour match

I used Paints4U for the paint for my spoiler, and the colour match was spot on



Also used them for a touch up kit on the Vectra.