So what kind of "apps" can you install and what do they do that you can't already do in a normal web browser?
from what I can see, most of them are just links to the Web Apps, placed on your desktop. there are some apps though. mostly its a function of the Chrome Web Store, which is mostly desktop-ized links to web apps. there are some actual Apps though, like Ebuddy.
I don't have many apps thus far, but from what I can see, even the ones that are just links are very well integrated into the OS. after all, the entirety of the OS is a web browser anyway.
you can install pretty much anything off the Chrome Web Store. https://chrome.google.com/webstore
the OS is nothing more than a Platform for the Web Apps to run in.
The computers running this OS are going to need to be insanely inexpensive in order to gain traction. there is very little that this OS does that you can't do in the regular Chrome Browser, from my limited experience so far.