1) His gender and general nature. He's not the typical Fluttershy healer who is all nice and friendly. Snakebite's a male healer and not the nicest pony found, but he'll help. I also like that he is more in tune with the way the Wasteland works than other healers.
2) He isn't defined solely by being an alicorn. He has his history with his teacher, giving him insight to zebra culture and customs. He likes energy weapons over regular guns. He is mature, and not easily riled up. Those little things help making him much more than yet another alicorn reawakened.
Also, I like the much more smaller scale style of the story, and focus much more on the towns that were created after the megaspells hit. That combined with Snakrbite's own history of growing up in the wasteland, offer a different and less negative view on the setting than say from Littlepip.