Hi folks,
we're collecting some categorized examples of WL in use here, to better understand how it's being used and what the pitfalls may be.
http://www.mediawiki.org/wiki/WikiLove/Stories
So far, we're seeing lots of examples of use exactly in the way it's intended -- new users thanking each other, experienced users thanking new users, experienced users thanking or congratulating each other. Lots of new users use it on their own talk pages, which can be a bit annoying, but we think having it enabled for experimentation on your own talk page is probably the most intuitive way to learn how to use it. IMO this actually has some potential additional value as well, as it can give you some insights, e.g. whether you're dealing with a hardcore vandal or just a kid experimenting and clicking around.
We've been talking about a potential throttle to deal with overuse. These and other ideas are being collected here: http://www.mediawiki.org/wiki/WikiLove/Idea_Log
And, as a reminder, the feature is highly customizable by any admin following the instructions here, or by any user in their personal JS: http://www.mediawiki.org/wiki/WikiLove#How_to_customize