I'm not a big fan of milk chocolate bars as a rule. I tend to associate them with bland, waxy, mass market "candy" like Hershey bars. Or I find them to be overly sweet, as I do many of the Cadbury milk chocolate bars.
The technical differences between "dark chocolate" and "milk chocolate" kind of depend on who you're talking to, and what country they are in. As a general rule, dark chocolate is cocoa plus fat and sugar. Milk chocolate is cocoa plus fat and sugar, AND milk. Take a perfectly good batch of dark chocolate, add some milk, and there's your milk chocolate.