The capabilities for inventory management and shopping cart/catalog rules (promotions and discounts).
Order management seems good but we haven't used it too much (we proccess them throught another system). SEO seems pretty fine. It's a powerful system but maybe you don't need that much.
The complexity of the system. The ecosystem is poor: few plugins and extremely complex to make them work. Too expensive also if you want to find reliable alternatives.
Making changes is complex, Magento has 20,000 files and it's over Zend (PHP Framework). That makes changes too hard.
There are some templates but definitely it's not that there are too many options as in Woocommerce.
The system is pretty heavy so be ready to spend on resources for your server.
It seems like too much to me.
They say that Magento is for larger businesses.
For me, TLDR:
- rules and promotions work nice
- cache implemented
- robust enough to scale (many features to manage high volumes. Magento Entreprise is available too for that)
- inventory management has many options for variations, bundles, etc.
- Hard to grow. Marketplace is poor, few choices. Woocommerce is way better and quicker.
- Making changes to theme is too complex. Over 20,000 files in total. Forget about anything, Zend is painful.
- Too heavy, high server resources.
- User management (for customers) and checkout process sucks.
In the end, I wouldn't choose it again. I'll go with Woocommerce, powerful ecosystem, lightweight and easy to customize (in fact, we are migrating).
We are using it as an eCommerce for our company. We connected our API to Magento (not easy and we still have problems).
We needed to connect some third party plugins, very hard and prepare to suffer Magento pain. Random errors when installing plugins.
Making theme changes is long and complex. Definitely could have been easier.