[SOLVED] Allowing all URI characters

[eluser]misplacedme[/eluser]
I'm toying with codeigniter, and ran into an issue that I need an answer on.
I'm wanting to have user-readable search queries based on the address (index.php/users/search/tom*)
Of course, I get a message saying that I have illegal values in my URI. I don't want to base64 encode my strings, and the only thing I can think of to allow this is to allow all URI characters.

What exactly are the repercussions of doing this? As far as I can see, it will just mean I will need to do more sanitization than before. Correct me if I'm wrong.