Used it in the past (on a different computer). Don't particularly like it. For one, it adds another network interface and tends to break programs that are too dumb to listen on all of them instead of just one (boggles the mind, that does, when it's easier to listen to all interfaces than to a specific one). For two, [complaints that may or may not be outdated about the maximum number of users in a network filling up, and then having to start a new network, which ends up with connectivity issues, etc]. For three, because people can't figure out port forwarding? Well, technically, not entirely, some people use it for (a) older games that no longer support internet multiplayer, or (b) because they've pirated something and it won't actually LET them play internet multiplayer, and Hamachi lets them get around that by playing a LAN game through Hamachi instead, which many games allow (which is probably why Blizzard didn't support LAN games in Starcraft II). But I'm not in either of those categories.
I haven't played anything multiplayer that lacked internet multiplayer in a long time now, and port forwarding isn't a good enough reason for me to install it on this computer.