Physically, Echidna is very striking. While that's kind of cool, her style is nevertheless warped. :X It's a good thing that she's beautiful and can pull it off. I'm unsure of how to look at her appearance. She looks cool, in one light, but on the other hand, she also looks gaudy and freaky. Her fashion sense may also be somewhat influenced by her inferiority complex- she wants to stand out and be noticed, and her physical appearance definitely serves that purpose well.
Echidna's issues with Volt, her feelings of being underrated and her schemes, some of which involve murder, are kinda 'eh...' Still, it would be tough being a strong female who constantly is treated like a fragile piece of porcelain all the time, or at least thinking that's how you're being treated. I believe Volt cares about Echidna, but he doesn't give her the respect she actually deserves. Hence, Echidna's hostility leads her to framing him and so forth.