Key benefits of Magento include:

• Open-source Specifically made for eCommerce
• Great discount system
• Payment gateway integration is easy
• Flexible and customizable
• Very powerful admin panel
• Highly scalable
• Once optimized (vanish, db optimizations, redis caching, opcode caching)
• Magento can be quite fast
• Multi-tenant support
• SEO-friendly
• Large user base, actively developed, secure

Known issues include:

History of open-source has left it with an enormous, overgrown code base that does everything, and leaves every door open to customization. It is also a plus point of it.
Development is expensive. Partly because it’s hard, and partly because it’s a popular system.

Expensive server requirements

So We Let’s consider the major factors in the decision making process:

• Your Business Plan
• Budget
• Product Catalog
• Functionality
• Interfacing with Other Systems
• Maintenance