Disadvantages of the Feistel network I have read about Feistel network and so far only advantages have been listed. Are there any disadvantages to the design? Please could you explain in fairly basic terms?
Well, what are we comparing Feistel networks to? The other major design paradigm is SPN: https://en.wikipedia.org/wiki/Substitution-permutation_network. In comparison to SPN, the cons are:


Not a direct implementation of confusion and diffusion. Feistel networks have more structure that has no clear justification. (Some point to the security proof but if you assume a cryptographically secure round function, how wrong can things go? A better question is: "if your round function is weak, what does the Feistel network add?").
Parallelism is about half of an equivalent SPN, which is a disadvantage for hardware implementations.