The pros (at least for me):

- You host/own it

- It's not centralized: every node can sync with the others

- Seems to be fast (the more nodes, the merrier)

The cons:

- Setup is slightly more difficult (you need to share some keys and ips)

- No iOS client (not an issue for me)

- You can't share a folder or file via web link

So it's great for syncing folders between systems, but it doesn't substitute the job that something like Seafile would do (managing permissions, collaboration, web file sharing, fancy web ui...)

There's a bit of info in the faq: https://docs.syncthing.net/users/faq.html