I think it's pretty stingy, really. I order from a UK retailer called 365games, and generally they do 5-10% cashback on retail purchases (which are always priced below the digital equivalent). Unless it's DLC or digital only, I'm unlikely to ever get the 5% cashback rate from Nintendo, so my points will pile up very slowly. I guess I can see it as a bonus on top of the cashback I get through 365.
It's something, and it's been easy to link My Nintendo to my Switch and register my games for points, so those are plus points - but it's not a huge step forward and it shouldn't take Nintendo a year to roll out a basic reward system like this. I love my Switch, but eShop and the UI needs an overhaul - and they need to get Switch Online right, too.