I think the Freecycle groups are local, volunteer-run lists and some are easier to deal with than others. I've used both Freecycle and Craigslist to give away items and what I like about Craigslist is that you can delete your post once your item is gone, but in Freecycle it lives on and people have access to your e-mail address. (You can disguise it on Craigslist.)
I gave away a lawn mower on Freecycle and it was out of my shed within about an hour of posting. So from that standpoint, yes, it was very successful.
However, even though I sent a follow-up e-mail to let the group know it was gone, people kept e-mailing and asking for it. I sent a polite, brief reply to each saying I was sorry but the mower was gone. One poster sent me 3 or 4 more e-mails begging for the mower, explaining that she "really" needed it and requesting that I get it back from the recipient and give it to her instead. I really regretted that this person had my personal e-mail address and could with about 2 minutes of online research figure out my full name and address.
Ultimately, I think there's a weirdo factor on any sort of giveaway list, but I think Craigslist adds a layer of anonymity that I prefer where I can ignore odd replies and limit strangers' ability to trace me. After posting the mower, I did question the wisdom of making my identity and location that easy to uncover. I am still a member of my local Freecycle but I don't know that I would list something there instead of on Craigslist.