Meta-key in terminal does not work
Key-bindings involving a meta-key, e.g., M-x, do not work in terminal mode. The reason is that the (kbd "ESC") binding is overwritten in evil-maps.el, but all bindings with meta-key in terminal mode are signalled with ESC as prefix key.
Therefore some special magic has to be done intercepting the ESC key when used as prefix-key. viper and vim-mode both do this using some special key-binding on ESC with timeout (look for //vim:intercept-ESC-mode// in //vim-keymap.el// of vim-mode's source).
Furthermore, in X mode it may be better to bind [escape] instead of "ESC" (in fact, the signal arriving from the system is [escape] which is converted to "ESC") and leave the "ESC" binding unchanged. This way the Emacs alternative of pressing "ESC x" instead of "M-x" should work in X mode, too (in X "M-x" and "ESC x" are different events but the first is eventually remapped to the second, in terminal mode both events are the same, namely "ESC x").