That's really a matter of opinion. Some people think it's worth the money, others do not. In other words, it's not really a question we can answer for you.
Assuming you've already familiarized yourself with .Mac through Apple's website and you're still on the fence, I recommend signing up for the free 60 day trial, and perhaps purchasing a one year subscription after that. If you find it's not worth it, there's no need to renew.
Also, many have reported that you can find .Mac licenses cheaper on ebay.