No, Hamachi isn't safe. It can be fine for a few weeks, But after that, you start to receive virus' which may stop you accessing the internet, as it did with me.
So i advise you not to download it, Or use it with any strangers, Only friends you can trust. They can see your IP and that, And find out where you live.
If your on a Mac, it might be different, I think Macs can't get some virus' and protects your pc. But still, don't download it.
If you do get a virus from it, Go to Safe Mode and delete it as soon as possible. Always scan it with a virus protection softwares before using it.