PrestaShop is an impressive new entry to the field, with a very attractive user interface and impressive product option/variant capabilities (like Zen Cart attributes). One downside is that it's much harder to modify; there is nothing like the Zen Cart "templating " capability so you're always changing core files. This gets hard to manage with the frequent release schedule PrestaShop is using. But you should definitely install it and spend some time testing it and evaluating its suitability for your shop.
