The Lake Sentani festival is the 'Disney tour' option to experience West Papua. Overall it's a slightly sterile version of life in the region however it is an effective way of experiencing cultures you might never otherwise see. As part of the festival a crocodile is captured and slaughtered - if this offends you then don't attend. The festival itself is in its infancy and if you're visiting Papua around the time then it's well worth it but I can only give it 3* on the grounds that it's simulated rather than completely authentic.
A more authentic festival is the Baliem Valley festival which is reviewed elsewhere. From 2009 the Lake Sentani festival will be timed to support the Baliem Valley event and in combination is possibly the easiest way of experiencing tribal life in West Papua. The two festivals + visiting a Dani village (from Wamena) or two would be the most 'complete' way of seeing West Papua in a limited time period.