We are homeschooling ds14 and did homeschool dd8 until about a month ago. Ds14's issue with school was unusually poor academic fit - needing more challenge in some subjects and fewer timed tasks in some (gee, try to get that sorted out with a school admin or teacher!)

Dd's issue seemed to be that she was turning into a tv character (and not one of the nice ones!). In addition to no more disney teen channel, among others, we pulled her out of school to see if this would help with an attitude adjustment. In some ways it has, however she became pretty frustrated with lack of social interaction in general. She wasn't always a girly girl, however she does need much more human contact than the rest of the family, and we mutually were driving each other crazy.
(There is actually a question of adhd which we are working on figuring out).

Curriculum-wise, I have always been able to find great books to work on with ds, however dd was usually bucking whatever I found for her after about a week or so. She would grudgingly proceed through whatever we'd selected. Last fall I finally found a science-reading book for her, and mostly we work on that, math and regular book reading (h. potter, etc.) We allowed her free rein in the last few months on minecraft and she has become quite an expert, reading a lot regarding building, etc. Previously she had a fairly severe tracking issue which appears to be 99% resolved (still wears the glasses prescribed).

Ds will be going back to the high school in the fall, as they have a stem program, one path combines design (he is huge into animation and drawing) and programming so it seems to be ideal in some ways. Removing him from the middle school grind was a very very good choice, I think.
The main reason I am hopeful about the high school is that his older friends that are already there express a good level of satisfaction with the high school - some of them having had real issues when in middle school.

Homeschool has been a wonderful thing for both the kids - refreshing their attitudes and self esteem.

*fingers crossed*