I use this a bit - the You Only Look Once implementation is good & fast (should be - redmon wrote the paper http://arxiv.org/abs/1506.02640) and it's all C. I don't think it's competing to overtake Torch/Caffe/Tensorflow as 'the' framework. What I find it good for is looking at the source code and trying to understand how something works in code (often not easy even after reading the papers) - easier than with the big frameworks. Also may be a good place to start for simpler target platforms e.g. embedded. Kudos to pjreddie.