Paper:
Training recurrent neural networks (RNNs) is a hard problem due to degeneracies in the optimization landscape, a problem also known as vanishing/exploding gradients. Short of designing new RNN architectures, previous methods for dealing with this problem usually boil down to orthogonalization of the recurrent dynamics, either at initialization or during the entire training period. The basic motivation behind these methods is that orthogonal transformations are isometries of the Euclidean space, hence they preserve (Euclidean) norms and effectively deal with vanishing/exploding gradients. However, this ignores the crucial effects of non-linearity and noise. In the presence of a non-linearity, orthogonal transformations no longer preserve norms, suggesting that alternative transformations might be better suited to non-linear networks. Moreover, in the presence of noise, norm preservation itself ceases to be the ideal objective. A more sensible objective is maximizing the signalto-noise ratio (SNR) of the propagated signal instead. Previous work has shown that in the linear case, recurrent networks that maximize the SNR display strongly non-normal, sequential dynamics and orthogonal networks are highly suboptimal by this measure. Motivated by this finding, here we investigate the potential of non-normal RNNs, i.e. RNNs with a non-normal recurrent connectivity matrix, in sequential processing tasks. Our experimental results show that non-normal RNNs outperform their orthogonal counterparts in a diverse range of benchmarks. We also find evidence for increased non-normality and hidden chain-like feedforward motifs in trained RNNs initialized with orthogonal recurrent connectivity matrices.

Review:
The focus of this paper is on exploring non-normal initializations for training vanilla RNN for sequential tasks. They show on 3 different tasks, and a real-world LM task that  non-normal initializations of vanilla RNNs outperform their orthogonal counter-parts when particular forms of initialization are considered. 
Although the results for sequence task do not outperform the gated counterparts, the authors present an interesting exploration of initializing non-normal RNNs that outperform the orthogonal counterparts. It is good to see this line of work being explored as an alternative to exploring more complex architectures with many more parameters than necessary for the task. 
Strengths:
    1. The paper explores non-normal RNNs and demonstrates on  3 synthetic tasks - copy, addition and pMNIST - how with careful initialization the proposed approach outperforms their orthogonal initialization counterpart. This line of experimentation is interesting as it potentially opens the door for more expressive modeling for sequential tasks by expanding the solution space of the weight matrices being learnt i.e orthogonal matrices are a special case.
    2. The authors do a great job in motivating the paper, and the explanation is clear and easily understandable. The toy simulations in Section2.2 really helps drive the reasoning behind why chain initialization improves over orthogonal initialization.
    3. Based on the insight from trained RNNs where the trained  weights exhibit a chain like structure, the authors attempt to modify the LSTM gate initializations well. However, they do not see any specific gain by doing so, and moreover they show analysis that demonstrate that the LSTM gates do not learn these chain like structures. However, they do have insight into the regularities of these learnt weights which could potentially open the door for more interesting initialization methods for training such gated architectures.
Issues to be addressed in the paper:
1. The plots are quite small and hard to follow. Can the authors enlarge these so they span the entire page? Also, for pMNIST it would be good to provide accuracy scores as well as a function of the training epochs.Finally, it would be good to include a comparison against LSTMs (and even Transformer networks) so it is easier for the reader to see where these approaches stack against architecture changes.
2. The authors are missing a reference to this  work - http://proceedings.mlr.press/v48/henaff16.pdf  - which provides empirical analysis for the 3 synthetic tasks to test the ability of vanilla RNNs for solving long span sequential tasks. 
3. What about stability of these non-normal RNNs? For example, if we perturb the inputs to the training for the LM task how much variance do we see in the performance of these models?