I visited just one of the churches listed, San Agustin in Manila. It is the oldest of the churches and I thought represented the site quite well.
There are two sections - the church itself and the attached monastery. Both are beautiful and very well maintained. I found the monastery really interesting because there are a lot of exhibits of artefacts and information.
Perhaps not surprisingly, the information presented was very biased. If you take it at face value, you would believe that the natives welcomed the colonising Catholics with open arms and converted straight away. Personally, I think it's a pity there isn't a more realistic depiction of what happened centuries ago.