TensorFlow makes some things difficult in truly baffling ways. For example, the last time I checked there's no built-in way to get gradients w/r/t say a single

TensorFlow makes some things difficult in truly baffling ways. For example, the last time I checked there's no built-in way to get gradients w/r/t say a single weight, rather you get a gradient sum. So if you want to do anything with the Jacobian (e.g. contractive autoencoders) you are better off using Theano.