Since your device will be performing NAT then it should at least give you some sort of security for those machines behind it.
I have heard mention that using tethering via a mobile device when in public is much more secure than public wifi alone... but I dont know any more than that Im afraid, but it may give you some where to start searching.
Ah yes, I'd overlooked the fact that NAT provides some degree of security. That makes me feel less of a wally though next time I use it for the Mac I'll batten down the firewall first.
I can also well believe that tethering is more secure than public WiFi as at least you can be reasonably confident there's no unwelcome presences on the LAN. And you certainly can't assume that hotel Wifi is firewalled, or even professionally configured.
I recently stayed at a hotel which bizarrely provided, in place of a TV, a MAC PC. The idea was you could use it for email, and web browsing too. But interestingly, when I browsed in OS/X 'finder', I could 'see' all the other hotel rooms' as network shares, identifiable by host names that included the room number.
I resisted the temptation to actually try to connect to the other rooms' Shares, but felt a lot more comfortable using it just as TV, and the iPad for email with Android tethering.