Helio Ocean and Attachments

A commenter asked how well the Helio reads attachments.
Basically it comes down to a couple of things, one it only seems to read images (jpeg, gif and png) sounds (mp3 is all I've tried) and html attachments. As for things like PDF, Word Docs and the rest not a chance. What I end up doing is using gmail and their preview or read as HTML seems to work well enough.