I have no real peference; however, that's because everything I do is direct either on LAN or Desktop.
Sharepoint has its quirks
VPN or other methods, I really advise that the client has a local install of either the Full Access or the Runtime and has a local copy of the front-end file.
This front-end file should have all of the forms and static tables, queries, and other stuff that normally doesn't change. Optionally, any tables that do not change very often, say no more than a few records every year, should be considered for the front-end file too. You can either code to check the back-end for updates or simply push a new file out and have a version check.
VPN, is not your friend for Access; however, many people have a very good experience with it and yet others go thru hell. As for multiple people via VPN, yes provided the database is split as above. Here again, the number of contections depends on the database design, etc...
BOL
-z