I have tried other services like this one in the past and eventually left them as they weren't effective at updating plugins consistently but after using this service now for a few months I finally feel that I have found the right tool to manage client website updates safely and effectively.
For me one of the most important things is knowing exactly what got updated when in case something goes wrong with a website. Being able to look back at exactly what got updated when makes it much easier to work out what happened and fix it quickly. With the backup option you can also just roll the site back to the day before you had the issue so there are some fantastic contingencies there too.
I have to also comment on the support as that for me is equally as important as the functionality. I had an issue with a site not syncing and sent in a support ticket that was addressed within hours of submitting it with an excellent explanation of what the issue was.
For me its the perfect tool for a web developer supporting multiple clients sites long term (which provides a steady income outside of just building websites).