reddiquette can go a long way towards making sure that you enjoy your experience. Like any public forum, there are trolls but if you ignore them they will usually go away. Everyone gets along pretty well for the most part though. Overall, I've found it to be a great place to connect with fellow tea lovers and share information. There does seem to be a bit of a group bias against Teavana but they usually keep things within reason.
Reddit is a little hard to navigate at first but once you've subscribed to a particular subreddit it will automatically show new messages from there on your home page. I spend a lot of time commuting by public transit so I use a mobile app called Reddit Is Fun. It's a great time killer for when I'm waiting for my bus home.
Here's some of the subreddits involving tea to start you off:
This is where the bulk of the conversations about tea happen.
Not as active but this a great place to post anything that is specifically about green tea.
Slightly more active than /r/greentea. If you have a question specific to oolong, post it here.
This is the place to share all of your pretty tea pictures.
A place for fans of dark teas to hang out.
Got anything to trade? This is the place to post it.
A place for the traditionalists to discuss gongfu brewing,
My friends at +Boston Teawrights recently set up a subreddit for their customers to be able to share and learn about teacrafting.
To make things even easier, check out my curated multireddit!
A Note for Retailers:
Just as with any other social network, there are right ways to use Reddit for business and there are wrong ways. Be human, be authentic and share your knowledge. The community will see right through deceitful tactics (such as pretending to be a consumer and recommending your own company/product). Answering a newb's questions gives a better impression than a sales pitch. There are a number of retailers who have done really well thanks to this forum. You can be one of them if you keep it real!