You should look at their official material. Their mini sectional tests. One of the questions had 6 options!! Numerous spelling mistakes, 'that' instead of 'than'.
Rather than State Owned, it was written STOWNED, AND THAT WAS THE CORRECT ANSWER!!
WORST EXPLANATIONS EVER.
Consider a sample CR question, the answer to which is, suppose, option D.
Solution:
Option D: Correct
Others: Irrelevant
AND of course their Youtube channel. The instructor of one of the SC series suggests to solve simple SC questions under 10 seconds! That is STUPID.
Regarding the faculty, I believe, it depends on the Branch you are in. I was lucky enough to get a good cooperative staff.
Based only on the staff, i would give jamboree 2.5/5
Based on the common material (Website and Youtube channel), I would give it 0/5.
Overall, i do not recommend Jamboree.
Magoosh/Manhattan, OG, and GMATclub are more than sufficient.