Plugin functions well though I'm getting about 3-4 404s on various UI images that aren't getting loaded. The image paths are looking for an "images" folder inside the plugin folder but there's no folder there. I can style via my css file but the 404s can potentially be taxing on a high-traffic site.
I'm also getting a js error: jQuery(...).ready(...) is not a function - Looks like this is due to some stray parentheses at the end of your jQuery function in accordion.js line 3. () Removed those and that took care of the error.
Would be great to get an updated version with UI images included and parentheses removed. Plugin functions great even with those small issues but just thought I'd bring it to attention.