Magento is a great e-commerce platform, really feature-rich and easy to extend. But what makes Magento really great?
I have a couple of points that I really like about Magento:
Great community
Magento really has a huge online community. If you’re stuck when working with your webshop, or programming some custom functionality, you can find an answer online on the Magento forums or on Stack Overflow 9 out of 10 times.
Excellent code base
Where Magento differs from a lot of other e-commerce and content management systems, is the nice and clean object oriented MVC model. If you follow the Magento guidelines, you will end up with very structured software. This is not only good for developers, but also good for webshop owners that buy or download Magento extensions. In my experience the average Magento Extension is of much higher quality than the average wordpress extension for example. Of course Magento extensions are also more expensive, but I guess in this case quality is the most important factor. Your business depends on it!
A boatload of features
Magento offers a huge amount of features. Much more than any other e-commerce system. This is really where Magento differentiates from the rest. It’s literally a beast! Maybe a bit of a slow beast, but that’s nothing that can’t be solved with some good ol varnish caching 
What do you guys think are the strong points of Magento? (and maybe the weak ones?)
Let me know in the comments below!
Cheers,
P