Reading files from network shares is OK with Logstash's file input. 
One thing to be aware of: Some network filesystems (nfs) have aggressive client-side caching that cause Logstash to be lied to about the state of the file - this caching prevents Logstash from detecting new changes in files on those nfs mounts.
For windows, Samba/CIFS I think, I can't recall anyone having trouble with this, so it should work fine. Of course, let us know if you find otherwise 