I agree with @Photics,
But also Apple have been venturing into cloud based apps for a little while now, Numbers, Pages etc. But every time I have used them I have run into a brick wall with their lack of features that the real apps have and I then cannot wait to get back to doing what is needed with the real app.
These web apps for me are only for convenience and not something I would wish to be stuck on.
I also believe that to maintain a web app in the long run may be harder, due to the fact you have no control over all the web engines. And would constantly be sifting through bugs due to another update that has changed something that should be standard across all browsers.
With updates to native apps APIs I think you at least get some lead time and notifications of most changes and also a bigger gap.
And as a end user I have yet to see a web app that works as well a native app..