I used ecwid for a client recently. No headaches at all.
Smooth, works great. Started selling the same day it was launched.
You may need to dig deep into the css customization, and hyperlinking if the widgets are not up to design standards, Other than that, it works as a standalone mobile shop, as a part of any programming language, html, php, whatever.... and the wordpress plugin adds a lot given it sets up the SEO for you if you're an ecwid payin member.