My DD is currently in 5th grade at Garrett Park.
Most of the teachers we have had were very good. In six years, we have had two classroom teachers and two subject teachers who were young and not very experienced, and one classroom teacher who yelled. (Many other kids and parents liked her, but for others her style was too forceful.)
The new facilities are fabulous.
I have not had any personal experience with bullying. Another parent once said that she felt her daughter was being excluded by the "popular girls", but DD seems to be oblivious to this, and is friends with all kinds of kids. I can also tell that they take bullying prevention very seriously. The counselor takes the time to get to know kids, and they are taught about being nice to others and what to do if someone bothers them. (Move away, tell them to stop, etc.)
I think overall it is a warm and nurturing environment. It is a small school. The administrators know all the kids by name. The parents are very involved, and not just the SAHMs either. A lot of working moms and dads find ways to help after hours and are encouraged to do so.
Living outside of the town of Garrett Park, it can be hard to make friends with the in-towners, who have all known each other for ages. In our five years at the school, neither I nor DD have ever been inside a house that is in Garrett Park or GP Estates, but we have both made many new friends in other neighborhoods assigned to the school. Of course, this could just be coincidence. I don't know what percentage of students are from GP proper. It might not be that many by now.