Chris DiBona is the director of open source at Google, and he's been taking a big part in the open source and Free software ecosystem for a very long time--not least in his role with Google's Summer of Code. He recently posted on Twitter what he calls "a little rant" about software licensing -- well worth reading the whole (short!) thing. 

Upshot: Be cautious and humble in selecting a software license; ones that have been around and used happily by others have advantages, including familiarity to users. This applies to open source licenses, but maybe not so surprisingly at least as much to licenses that offer some of the qualities of open source (availability of code) without all the freedoms that FOSS developers have come to expect. 

New licenses, especially ones with complex restrictions on use, can make users shy away from them.