I use SAMBA to run file/print on my home network, but not Domain logins. I admit, SAMBA would probably be easier with a Domain auth model, but doing it with local accounts is painfully difficult. I get it working, but it took some trial and error, lots of error.
That said, if I had a Windows network (and servers to match), I'm not sure why I'd bother with SAMBA for domain logons, print services, file shares, WINS. That sort of thing is pretty painless with Windows.
However, if I didn't already have the Windows server, then using SAMBA makes more sense.
Chris