There's too many negatives about ChromeOS.
1. Cloud Computing.
If there's anything the last few weeks have shown us, it's that no information is truly secure. Information stored on Google's servers is no exception. Cloud computing relies on data being transferred to and from Google's servers. For those willing to put forth the effort, this information can be intercepted during transmission. If someone chooses to do their taxes on a ChromeOS notebook, that data is a moving target for those wishing to commit identity theft.
2. Internet connection REQUIRED
Most people don't want to pay a monthly subscription fee to use a computer. Since ChromeOS relies on "cloud computing" you'll have to have either a Wi-Fi connection or wireless internet connection. If you choose to buy it through Verizon, AT&T, Sprint, etc, you'll be forced into paying a monthly fee to use your ChromeOS notebook. If you're in an area with unstable internet service, you may experience peroids of time where the notebook becomes completely unusable. If you lose power and don't have a wireless internet subscription from one of the cellular providers, again, your notebook is completely useless.
3. You get what you pay for....unless it's ChromeOS
Most people actually want to own their software...at least as much as the EULA permits anyway. With ChromeOS and it's "cloud computing" approach, you don't really own anything....except the notebook. You're stuck with an OS that is essentially featureless, aside from a browser. The software, however, resides on Google's servers and thus you don't actually own it. Instead you pay for access to the software. Also, you're paying the same price as you would for a full featured netbook, with considerably less functionality. At least with a netbook or budget notebook, you can get a full featured OS....where YOU make the decisions about security.