Robert Jackson (United States):
I visited some 20 Jesuit mission sites in Paraguay, Argentina, and Brazil, including San Ignacio, Loreto, Santa Ana, and Sta Maria la Mayor. There are other mission sites in the region that need protection and the support that inclusion on the UNESCO World Heritage Sites lists confer. At the top of the list I would include several mission sites in Brazil, particularly San Lorenzo Martir, and San Cosme in Paraguay. Other sites, such as Corpus Christi and Martires, need protection and rehabilitation. Date posted: June 2005 Davis C. Bales (Brazil resident; U.S. citizen):
San Ignacio Mini is well worth the visit for anyone at nearby Iguassu Falls, whether on the Argentine or Brazilian side. Though there are guided tours available from Iguassu, driving on your own is quite easy. It is possible to drive to San Ignacio and back in the same day though spending the night adds to the experience. However, the town offers few accomodations, the best of which are hard-pressed to earn a 1-star rating. From Buenos Aires it is not so easy to reach Argentina's State of Misiones.
On certain nights there is a sound and light show. The slightest hint of rain and the show will be cancelled; the equipment is simple and not water resistent. So, as can be expected, the show is rather primitive and its simplicity could hardly be expressed as charming. Boring may be a better descriptive. The lighting is uneventful and the sound is a recorded narration (in Spanish) of the mission's history with some music of the jesuit-educated natives as a background mixed with some booms and crashes to depict the battles with they fought with the Brazilian slave traders. Not emotionally stirring!
In the summer it is barely dark when the light show begins, reducing even more the already limited effect. Needless to say, it was a disappointment and one should spend the night to experience the simplicity of the village and not for the light show. But catch it if you are already there and reach your own conclusions.
All that said, I would recommend making the effort to visit San Ignacio Mini to anyone with an interest in South American history or who enjoyed the 1986 Academy Award winning film "The Mission" starring Robert DeNiro, Jeremy Irons and Liam Neeson. Walking tyhrough the mission's grounds is walking through history. In the past 2 years I have made the trek twice by motorcycle from Rio de Janeiro and have a feeling I will return.  
Have you been to Jesuit Missions of the Guaranis: San Ignacio Mini, Santa Ana, Nuestra Señora de Loreto and Santa Maria Mayor (Argentina), Ruins of Sao Miguel das Missoes (Brazil)? Share your experiences!