3dcart is one of two eCommerce programs I recommend/use for clients looking to implement an online store. It is easy to set up and use and a good value for the dollar for those that are not experienced with running an online store.
SEO - 3dcart is built in such a way that even if you do no SEO work at all, as long as you use the meta description wizard on each page or product you wind up still searching pretty well in Google.
Product uploads - Product uploads are easy to do with 3dcart's .csv import/export feature. No need to struggle with messy simple and variable uploads like on WooCommerce, 3dcart takes the guesswork and hassle out of uploading different product types.
Media uploads - Media uploads are quick and simple and the uploader always works.
3dcart does not connect to many of the POS systems my clients use so we need to manually update inventory daily/weekly.
There are many modules available to do many different things, but it makes you feel like you are being tickled and died to death to get the site to do exactly what you want. Also can be confusing if you don't know what you actually need.
It's a little difficult/confusing to upload products with multiple variations - ie: color and size - especially if there are multiples colors and multiple sizes.
3dcart works well for small to medium size businesses that want to take care of their own website and product uploads and have the time to stay on top of inventory management. It does not work as well for a business who wants to just "turn it on" and forget about it unless they are able to integrate their POS system with 3dcart to manage inventory.