I didn't have a problem beyond resenting being forced to log in to retrieve GTA IV save game data.
Until my account randomly borked, refusing to let me sign in.
It took 5 weeks and several email & phone exchanges telling me to reset various Windows settings before the estonian CS team were allowed (their phrase) to escalate the issue up the chain to fix whatever was wrong with the account. Nothing particulaly epic, just drawn out.
Not had a problem since, althoug every time I need to log in to GFWL I experience a moment of panic if the login is not immediate where I wonder if the problem has come back. For this reason, more than the issue itself, I try to avoid buying GFWL games if an alternative exists.