I'm happy to see Nintendo develop a web app. They can really benefit from getting up to speed with modern online standards.
If I'm logging in to a website with my Nintendo Network ID account, maybe this is a step towards having it on a bunch of consoles, instead of being tied to just one. Here's hoping I'll be able to use the same Nintendo Network ID on my 3DS and on my Wii U some day.
One of the things that makes me hesitant to purchasing eShop games on my 3DS is the fear that if I lose it or something, I'm not sure how the re-downloading process would go on a another 3DS - though I think I'd probably end up bereft of both games and the console itself in that situation.
So yeah. It's good to see Nintendo getting on with the modern internet. A web app. Look at them.