I've tried almost any e-commerce component available for joomla, but all of them lack some important features for me.
Tienda is just perfect, the way you can customize any product/category view, excluding things you just don't need or want to show is amazing.
It's very easy to install and setup. The two modifications in the php.ini file are very simple to do.
Just one point: the translations should be a bit easier to access and to install.