I found it very good.
Basically - everything you do refereeing related can earn you points. At the end of the season, you send your logbook in - all your points can then be used as a currency. I purchased a full nike kit for example, and saved myself ~£60.
The number one fault is efficiency. I sent my log book in quickly, and didn't get an embodied kit - so my kit came around the beginning of August. I know many whose kit took many more months though.
This was a teething problem though - as the kit was new this season and there was certainly a shortage. There should have a surplus of kits now, so it will be much better managed this season.
Go for it. Save yourself money, whilst recording everything you do at the same time.
And no - I'm not paid commission by the RA-FA Incentive Scheme!