I find that having more than two speakers in headphones is a little bit gimmicky, the benefits from having more than two speakers is lost in headphones. This is because of how the brain interprets sound, the brain is able to determine what direction a sound is coming from by the volume difference along with the slightly different time intervals that the sound reaches each ear. This makes having multiple speakers in a surround setup very effective because it simulates real life where sounds come from many directions. This benefit disappears when the speakers are moved close to the ear, this is where virtual surround sees its advantages. Virtual surround replicates real life sound in a number of ways, such as offsetting the sound and volume from one speaker to the other to give the feeling of direction. That being said, there are benefits to surround headphones. In order to have proper virtual surround the user will either need a decent sound card, with out one virtual surrond is somewhat poor, or be listening to content designed with virtual surround, which can add to the overall price, or limit the availability of content.
This is a great video that demonstrates what virtual surround can sound like, just listen to it on 2 speaker headphones or ear-buds or something.