@polecat I think it depends. For me personally, it's building a web interface that doesn't suck in terms of architecture. That is, how the GUI is programmed (not how it looks). For the most part, web still sucks at this. I've looked at different frameworks like Ember and Angular and my personal opinion is that they do things wrong. That and also the fact that Javascript is ugly, so each one of those frameworks has to invent its own version of OOP. So I'm building it in Dart and so far it actually feels easier and I quite enjoy it.
As for the "polished already", keep in mind - it's a prototype. It doesn't mean that I currently only have a photoshopped image of the app - I have quite a bit of code written already - but it's gonna take time for it work. Any ideas of improvement are thus welcomed.