Zenefits changed my work life.
I used to have spreadsheets, pdfs, word docs, insurance forms and the hiring process used to be a spiderweb of isolated units.
With Zenefits they are all centralized and synced with payroll.
Hiring people takes me less than 3 minutes now and our employees can all self-enroll in health and disability insurance. Employees manage their own information, including adding dependents, requesting PTO, changing their address, changing their bank info for payroll, etc.
It's free, customer service is solid and the application user experience and interface are great.
I should give the disclaimer that my company helped them with their branding, but my review is completely independent of our experience working with Zenefits.