In my opinion, there's absolutely nothing wrong with venting. I think it's healthy, but there's a difference between venting and plain complaining about stuff. For instance, if someone has done something to me that has upset me quite severely, I'll rant about it. If I rant to someone about something but don't get the response I'm after (e.g. they disagree with me) then I might go to someone else. xD I don't like to rant a lot, but I'm definitely open to doing it when I think it's better to get something off my chest.

Venting is absolutely much better than bottling up problems, concerns and whatever else is bothering you. On top of that, venting can sometimes resolve issues, as you find comfort in other people's words and opinions on the matter. That's probably the best case scenario. ;]