Yeah, it's pretty good. You will only be happy with it if A) the scratches aren't too deep and B) you are very thorough.
It's a tough enough job to do it right but practise makes perfect. If the paintwork is oxidised (ie, red paint looking pink) it works a treat. You should wax the car properly afterwards too.
Try T-Cut Colour Restorer for small scratches / blemishes. Buy it in a colour that most closely matches the car's. There are even versions for metallic paints. The other suff can be lethal if you've never used it before.
Over-enthusiastic application of original T-Cut can damage paintwork permanently. The Colour Restorer version is gentler and much less abrasive.
The Halford pens are more for deep scratches / stone-chips and work very well if you have patience, a steady hand and good eye-sight to do the "filling in".