Used it a little before. They can be helpfull if your computer is having issues with long startup time and such.
Their uninstaller is decent but when it got the Antivirus in the System Care I stopped using it. (more antivirus isn't needed if you run win 8/10 and already have one. Meaning you run 3)
I wouldn't recommend them to anyone.
Revo Uninstaller is a better uninstaller than theirs.
CCleaner with CCEnhancer is better than their System Care program (you can also try Wise Care 365 and Auslogics BoostSpeed 8)
The programs I use are CCleaner and Revo, I definitely recommend them.