This was also my scenario.. 10 domains, one virtual server..
It took me about 45 minutes from "never done this" to "all sites done with a cron job for auto-renewals".
The final thing I did once everything was set up was donate to the project.
Setting up my 5 domains, hosted on one small (virtual) server instance was just a breeze. Esp. compared to my former experience with StartSSL.
And now, with a cronjob doing auto renewal everything is solved. So for me at least Let's Encrypt just made life better.