I use Code Block all the time for storing snippets of code. Even though it is very basic, it is still very useful to me as a programmer.
The biggest flaw that needs fixing is that quotes copied from source code into Evernote frequently get converted into the more stylistic, 'directional' quotation marks, even when posted into a code block. (At least they do for me on the Mac client.) This renders the code unusable without manually fixing all the quotes.