How have you found it? I've thought about doing that myself from time to time, and I would value anything you'd like to share about your experience there.
People's problems can variate from light ones to very complex ones so it's very important to have the adequate mindset, keeping in mind what you are doing there (offering support by listening) and where are your limits. If not, the frustration can overcome you.
It's not free of trolls but I have rarely found them there and the majority of the people is very grateful just for boosting up their mood, which gives you a good feeling after finishing a conversation :)