What can happen if i use a loose URL chars restriction?

[eluser]plainas[/eluser]
So lets say I want to allow users to create meaningful URLs, is this the correct way to output them?

Code:

$urlchunk = "/some?crazy!stuff;put;here\$byTheuser";
$urlchunk = urlencode($urlchunk); # Is this necessary?
echo htmlspecialchars(base_url().$urlchunk);

This is quite confusing, I what could happen if I would skip urlenconde call?

Just out of curiosity, if I allow the forward slash, i wonder if it will be picked as a parameter or if it will still work as the separator.