We found that the new Admin UI (we're using 6.4.2) properly submits a query with non-alphanumeric for searching, but that the clickable URL for that query does not contain URL-encoded characters. If using that URL to execute the query later, an incorrect query is executed.
If you revert back to using the deprecated Admin UI, it works fine.
Open the Query form in the Admin UI, and enter a query string containing punctuation characters, e.g. "http://someuri#123", and click on debugQuery.
The debug shows the correct query in the raw query string.
The URL produced for the query however is not properly URL-encoded:
If you click on this, the browser munges the query, and depending on the query and query parser, you may get a syntax error, the query string may get cut off, or you may get different results.
Drop back to the old deprecated UI and do the same thing, and the URL produced is fully encoded: