FlexPod uses NetApp Unified Storage which supports NAS or SAN, along with many networking, storage media, availability and data protection choices. You can scale a SAN up to 34PB on the FAS8080. Here's info on the entire FAS8000 Series for which we have new validated designs available. http://www.netapp.com/us/products/storage-systems/fas8000/fas8000-tech-specs.aspx
FlexPod gives you a converged infrastructure that is certified by both NetApp and Cisco as a vaildated solution. This means for you that the environment is easier to manage and support as you get a collaborated support model as well.
There are many reasons highlited but this is a hi-level.