I've given a Pre 2 as a first smartphone to several people. I think even though the it has a small app catalog and some quirks it is a good introductory phone because of the simple and intuitive way it handles some things. Of course I set it up before I give it, so it has preware and the patches and games I feel are good to have so they can enjoy the experience out of the box.
From their experience with it they like having a touchscreen and being able to play "angry birds" as well as having the security of physical keyboard for typing. The ability to have USB mass memory is good for copying music and movies. The introductory tutorial gets them used to gestures helps them get comfortable with the phone. The biggest downside is that help menus seem to need an internet connection to work.