Having grown up in Dekalb County (attended Fernbank Elementary) and now having two kids of my own with special needs (Aspergers for both and a mild PDDNOS for my youngest) I have some experience with the Dekalb County School System. My son went to K & 1st at Briarlake, but we decided to remove him and home school after 1st grade, simply because as an Aspy, they weren't able to cater to his strengths (reads and comprehends at a 9th grade level) and his weaknesses (significant social issues & difficulty w/ nonverbal cues). However, this does not mean that I think Briarlake is any less of a school. I think it is a great school for most people. My youngest is entering pre-k this year at Coralwood (they just do pre-k & K for a mixed student body of kids with various disabilities and standard HF kids), just down the road. So far it's been a great school and my daughter loves it.
But back to Briarlake, they are a very involved school w/ a strong PTA that feeds into Lakeside. (A higher rated school than DHHS) but not to put down DHHS, I just think that overall, LHS has a better reputation than DHHS.
As for middle schools, I really don't have an opinion. I don't like middle schools just on GP, but that's my baggage probably.
I recommend Briarlake & Lakeside if at all possible. Oh and if you have a son, join the Cub Scouts at Briarlake. It's a great program, but then I am biased.
Hope this helped.