Dave Winer wrote some interesting posts in the last couple of days on the future of apps.
Apps are not the Future
Enough Already with the Apps
The gist of his posts are apps can't link like the web. Thus in the end, the web will win out. And, I have to agree. For all the hype about apps, I still spend the vast majority of my time in browsers. Being able to link and share is what gives the Internet its power.
However, I gotta say the Mac app store is super useful. Buy an app, and you can install it on all your Macs. It saves money, time, and hassle. But I think the best apps like Dropbox and Evernote complement the web, they aren't walled gardens.