Merrimack High is an awful high school. The teachers are absolutely terrible, the school is very rundown, kids get in fights in the halls, drugs are everywhere. Overall, it's a very bad high school and I'm not impressed with the town of Merrimack.
I think this high school is what you make of it. I'm about to graduate in two days and I made some poor choices, but I've had a very rough high school career. My teachers, guidance counselors, assistant principal and principal all worked very hard to help me. Through their persistence in wanting me to succeed I'm about to graduate and go off to a fantastic college. I was able to walk out with far better art skills, language skills, writing, math(I can do well in now), and so on. Everyone that I have had for a teacher has been so supportive of my dreams and encouraging me to be better. One word of advise is If you take Portfolio it WILL challenge you to be strong emotionally. That class has prepared me for life and college like nothing else could. There are also MANY clubs to ensure you're focus will be touched upon.
This school is fine as long as your student does not have any learning disabilities. If your child is in need of or you suspect they will need SPED services, make sure you have an educational advocate or a lawyer. And make sure your representative is present at all meetings. Make sure you get and put everything in writing.