I have a Fulmer half helmet and a Fulmer full-face helmet. The first is just the plain ol' Fulmer half-helmet kind, and the second one is a discontinued youth helmet that I got for cheap on Ebay, so I don't think it really matters what the model number is.
I use the half helmet when I go to class because traffic (buses and pedestrians) keep my top speed to about 15mph and because I don't want to lug a full face around between classes.
I use the full face the rest of the time. Someone once posted a diagram... here, this one:
I find that pretty convincing, although I guess I can't say I've thoroughly looked over the study that produced it. I know that now that I've got the full-face, the one time I don't wear it will be the one time I'll need it, and I'm not sure I could ever forgive myself if something did happen and I could have lessened the blow by wearing a helmet I already had.
The half helmet is certainly less restrictive -- it's easier to talk, eat, or call someone on your cell when you're wearing one. You can also hear oncoming traffic better, and you don't have to turn your head quite as much to scan upcoming intersections for idiots who might run into you.
The full-face is warmer in general, which is good when it's cold or even cold-ish outside. It's hotter than the half helmet when you're stopped, but they're really pretty comparable in terms of heat/stuffiness when you're moving. I feel safer in my full-face.
There's an ongoing discussion about whether you want DOT or Snell ratings. Last I heard, DOT is actually safer than Snell for lower speeds (like those achieved on a moped), but I'd be surprised if that debate doesn't resurface here.
Yes, I also wear gloves. If I fall, I am most likely going to put my hands down to catch myself. That doesn't mean I'm not going to f-up the rest of myself, but at least the part that is most likely going to get the most damage is protected with an extra layer. Gloves are also an A+ decision when it's cold or cold-ish outside. As an added bonus, if you're really angry about something, you can strip them off and throw them on the ground angrily. It adds nicely to the effect.