Depends on your point of view.
I run a RAID 1 array which as you know is a mirror so that identical information is on both discs but obviously I only get half of the potential total storage space. If one disc fails then the other carries on and in my case the new replacement disc will have its mirror rebuilt. So it's good for data security.
What it cannot do is help with a malicious code because both discs are infected and if it is so bad the whole array may not be recoverable. Not that I have experienced anything like that. Also if data security is really important then keeping a copy away from the original is quite important eg if there is a fire at the base.
Now it's a matter for personal choice really but I run my RAID array with Acronis for back up, belt and braces really.