Our school used this when my kids were in elementary, though that was several years ago so I don’t know if it is the same edition, etc.
Overall, I thought it was a good program, and if state testing is your metric, then our district performed better than almost every other district with similar demographics. I think it does give kids a good foundation. However, I have heard stories about teachers whose implementation was inflexible and rigid- I think a lot depends upon the individual teacher. Also, our district supplements almost all the purchased curriculum with teacher and district-derived materials, so take that with a grain of salt.
For a gifted kid, or at least for my kids, the curriculum was problematic in a few ways. As you mentioned, it is group-focused, and the result here was that things moved very slowly for our kids. There was little to no opportunity for differentiation- a challenge problem (one!) at the end of a unit was typical. (Our school, though they talk about differentiation, was very much against it in practice, so this may not be a curriculum fault, though from what I saw I suspect it is). The other problem was huge amounts of repetition (again, in a more enlightened district this might not be the case- it would not be impossible to pretest and let some kids work on different material, for example). The curriculum is designed to spiral, I believe, so the same topics came up over and over, year after year, which was torture for my kids.
Some of these issues might be amenable to changes if the teacher/school are willing, but our experience was not great.
Hope that helps.
