depends...they tend to be a lot more reliable then windows machines, that's a pretty accessible advantage.

other than that, I feel like most of the advantages of unix systems come with either having some experience with them, or being willing to learn some of their underlying command line system. Personally, I love them. I work with webservers all the time, and so having a unix terminal at your fingertips can make things really simple. But, if you are not likely to jump into that realm, then maybe it's not a factor.