There is a major problem with Samba, in my experience in 16.04. I initially went back to 14.04 in frustration. However, it seems that some of the "improvements" in 16.04 have been "backported" (or whatever the term is) to 14.04. So, 14.04 is now borked with samba as well. However, this is not merely a problem with Ubuntu Mate or, even, Ubuntu. It is all derivatives of Debian. I have tested this in several such derivatives as well as Debian itself and the story is the same. Samba is buggered at the moment. It may even run further back that that and be a Linux bug running in the latest Linux Kernel. I have read of this issue with arch as well. Though, have not tested it recently to be sure.
The first issue is the damned thing just hangs when trying to access a samba share. Secondly, there is a nasty little bug called gvfsd-smb-brows that causes the CPU to run hot as hell at 100% usage. There is a fix for this that stops this bug operating. But, unfortunately, this causes samba to be completely inoperable.
For myself, I have got round this by completely disabling Samba and using ssh for networking. But this is because I only need to access other Linux machines. I don't know if ssh can be used to access Windows machines from Linux or vice versa.
Hopefully someone more knowledgeable on here can come on and confirm that.