Vantaggi
The best bunch of people I've ever worked with, genuine team spirit (not falsely imposed "corporate" team spirit), working on interesting projects in an environment where you're encouraged to embrace new tech. Little things that might go unappreciated, like the company ensuring parking spaces for all, a nice modern office, (unofficial) flexibility of working hours, but mainly (for me), the respect I've been shown since day one which has allowed me to do my job with confidence. Definitely a company I would be happy to return to one day, after I leave.
Svantaggi
Occasionally the CTO will impact our work outside of the regular workflow, usually for C-level reasons that aren't always clearly explained, and it can be difficult to context switch. But this is true of all CTOs/CEOs I've known.