Been given some Meguiars Scratch X.

Does anybody know if it is any good or if there is a better alternative and how often should you use it?

Only use it when required (i.e. to remove scratches and deep swirls), and work it hard to break it down properly (otherwise it will leave marring). It's an okay product, but in all honesty Menzerna Intensive Polish is better by hand for defect correction and thorough polishing. Either way, work with a German Applicator Pad rather than Meguiars Pads for best results. :)