I recently learned about Justworks. Has anyone used the service for their payroll, benefits, HR, and compliance needs?

I'm interested to learn about deploying this service (or that of any other PEO) in a small business that is going through a change of ownership. Let's assume a company with ~45 employees. Let's also assume that the current payroll and benefits package are all managed in house by a 1-person HR department that is overworked.

Thank you for any thoughts in advance!