There are a number of ex-pat high schoolers enrolled at the San Pedro High School.
One young lady that had just moved her last summer told me that she loved being here and was making friends easily - unfortunately she has to leave due to an illness in the family but she and her family have said they hope to get back to the island ASAP.
There is a young man also that just moved here and enrolled - is enjoying the change and is learning how to scuba and has made friends easily also.
The basic education at the High school is good, but your children will definitely need to apply themselves if they want to do well. All of the kids that I know that have graduated from San Pedro high and have had the chance to go on to further education in the US, Canada or UK have typically been A and B students. There will be holes in the education in regards to that nation's history and social studies - but math, English, sciences etc are, of course, the same.
You have the option of home schooling your child or there is also a night high school so if your child wants to dive, sail, fish etc during the day he/she can still obtain a full high school education at night school - but this will take a lot more dedication as these classes are more typically targeted at adults that did not have a chance to finish high school during their teens.