The wiki is one of those good ideas that does get used but just doesn’t have enough contributors. So everything that’s there is good ( and because it’s a wiki, gets updated much more than some of the threads in the forum), there’s just a lot of stuff that you would expect to be there that isn’t.
For example, there’s a crying need for a table of compatible devices such as the vera and securifi wikis have, but while there are categories for them, there just aren’t many entries. What will happen is every once in a while some developer will write a new smartapp or device type handler for a specific device and then they will go to the wiki and add information about that device, but nobody’s gone through and just filled in all the entries for existing Devices. So instead, we end up with just an FAQ like this:
It’s better than nothing, but it’s not a whole lot better than nothing. 
I myself rely on text to speech software and I can’t do tables in the wiki, so maybe I shouldn’t complain about this since I can’t contribute to that format at all myself. But as an answer to your question, the wiki is a good start but a long way from being a comprehensive resource.
The area that is kept up-to-date, does get used a lot, and I think is of significant value is the quick browse lists. Because, to be honest, while there is tons of great information in this forum, the search sucks. 
So when it comes to seeing other people’s project reports for holidays or kitchen projects or mailbox notifications, or finding smartapps for weather functions or microlocation or whatever, or a DTH for a particular lighting device, the quick browse lists are very helpful.
Please feel free to contribute anything you think would be useful to the wiki, more authors are always welcome. 