This ten year appraisal written by Drake Bennett for Business Week also features wiki-style collaborative editing by a small number of invited external contributors. It's not perfect but overall I think it does a good job.
There are some obvious errors which will be obvious to us all and may mislead readers less familiar with the inner politics. For instance the response to the Siegenthaler affair includes Jimmy Wales' decision to stop anonymous creation of new articles (correct but out of date as it was a temporary measure) but doesn't seem to cover the much more important policy shift.
The article overall is however somewhat more positive about Wikipedia than I would have expected as recently as last year. The press and blog response to the recent fundraiser was also overwhelmingly positive. I think we've finally broken the barrier and acquired an exulted status hitherto shared only by such institutions as the BBC and the NHS.
http://www.businessweek.com/magazine/content/11_03/b4211057979684.htm