I was tempted to buy chromebooks a few times as a student, but never did because of their tiny storage. They're meant to connect to Google online services, and to access all the stuff you've stored in the cloud. But they're very impractical to use as a normal notebook, you can't store much documents/photos or install much software on it.
Regarding warranty and software updates, the EU has minimum legal guarantee of 2 years, and new regulation is being discussed to extend legal warranty to 5 years, and to require repair service to be available up to 10 years in order to provide repair options after warranty expires.