I like how easy it was creating labels - you don't need much experience or know-how in order to create them quickly! You can use your own images as well (no other third parties are needed).
It's really cheap compared with similar tools out there so if one label doesn´t work just delete that particular instance of this tool from all instances where its used :) We're using v8 at my workplace but not sure yet what we'll do once they release their version 9 which has more advanced features such us segmentation capabilities etc... Currently solving problems related mainly around object detection / recognition however soon will be focusing our attention towards semantic analysis/segmentations also via machine learning algorithms applied mostly onto medical datasets e eg MRI scans.