Messenger Freedom is, as far as I know, an add-on for MSN Messenger, about the same as Messenger Plus!, but not finished, and that may take a while.
As it is not finished, there's not much to tell. Features that were mentioned were, if I recall correctly, things like more than 5 custom emoticons per message and file transfer resuming, which would be nice, but it's not finished, so it's pretty useless talking about it, I think
Currently, Plus! is the best, but who knows what will happen in the future
You might be interested in reading threads like
http://shoutbox.menthix.net/showthread.php?tid=21894 and
http://shoutbox.menthix.net/showthread.php?tid=19363.
Apparently NoName summarized it a bit 
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