With traditional browsers that live on your computer users are always susceptible to viruses and malware. In the event your plugins (e.g., Java, Adobe flash) are out-of-date that risk increases even more. So with browsers living in the cloud you don’t have such security risks.
A cloud browser doesn’t store data from your sessions (goodbye cookies and privacy tracking issues) and prevents malware from connecting to your computer. Another benefits of these browser are that they work with multiple operating system platforms (e.g., Windows, iOS, Android).
So, what is the one downside? They are not free. After any “trial periods” you pay either monthly or yearly for the services. But what is the price of your peace of mind and time “not spent” cleaning viruses and malware from your computer system?