- Plagiarism: A regular critic of the site, Daniel Brandt, recently came up with an analysis of plagiarism in its content. In fact, the samples weren't all proven so, but some were. Wiki's defence (and legally a valid one) is to remove offending items where spotted.
- Privacy: Incidental to the above, it is evident that the model can be seen as an intrusion on privacy.
- Suceptibility to hacking: the German-language version was recently hacked, to lead readers to malware.
It's worth bearing these in mind when using that resource, although in mitigation it can be said that a) the offences are small in overall proportion; b) offences are removed when discovered - which can be sooner or later, depending on traffic and the amount of alerts people store for a given article.
There's also a list of miscellaneous complaints posted at SMH that's worth a read. Gives a tenor of the concerns people have.
I'm still finding it useful, though. As a quick reference, I tend to find it more lucid, accessible, and reliable than anywhere else. In the link above, several people opined that it was more reliable than the newspapers (and other media) that are widely taken as gospel and more frequently read.