LightNet is plausibly useful for educational purposes, can be used to implement and train neural nets over small and moderately large datasets (maxsize after tiling can be of the order 10^6) in a reasonable time frame.
There definitely is scope of optimisation in the implementation, anyone intrigued enough should pursue it. To dive deep into how LightNet was built step by step refer the Jupyter Notebook 'Reverse_autodiff_py.ipynb'.
LightNet gave the results expected off a neural network when tested on a toy dataset and the famous coffee roasting example. Check out the respective directories to see the tests.