I have gone through the experience of using two shopping cart solutions, Magento and Zen Cart.
To understand Zen Cart, you should understand OSCommerce. Coming from the CMS world, I see OSCommerce as akin to Drupal. From the perspective of a pro developer, it is highly flexible and robust. To noobs like me, it seems very crude and basic. Just like Drupal, OSCommerce can give you a lot of options but comes with very little default features.
Zen Cart is like Wordpress. Very organized structure and highly optimized performance. Enough features for the small to medium sized e-commerce website. Easy to work with for rookie developers.
When I came on board, I worked on Magento. It was my own suggestion as I had heard many good opinions about it. Magento has almost every feature you can think of. Unfortunately, it is very CPU and DB intensive, making it extremely sluggish on shared hosting services (BlueHost in my case). Magento is comparatively new and therefore very buggy and the online stores I built running Magento (3 of them in all) experienced a lot of downtime. I see it as the Joomla! equivalent of shopping carts.
The reason I stuck with Magento was to prepare myself for a big move on the organiztion’s main online store that was running on Zen Cart. Magento had the feature of building multiple store fronts and store sites sharing a single database. This is a powerful feature that can allow you to churn out many specialized sites on top of the present site without much increase in required store management.
As I have preferred Wordpress over Drupal and Joomla, I also like Zen Cart over OSCommerce and Magento. I really love Magento’s features, but there doesn’t seem to me any future in it for me simply due to its sluggish performance (or, expensive hosting) and unstable releases. Unlike Wordpress though, Zen Cart development has somewhat come to a standstill for the past two years.
I don’t want to revert back to a two year old technology in Zen Cart, yet its alternative Magento lives in the future rather than the present. I am at a dead end.