While CiviCRM has undergone major updates and re-organization under the hood since the platform was started in 2005, it's User Interface has largely remained the same. This is all about to change with the introduction of the new Shoreditch Theme for CiviCRM.
This new theme modernizes the CiviCRM Interface in a thoughtful way, better utilizing screen real estate and creating consistent treatment of design elements to better highlight the things you want to see and minimize the elements you don't.
It's a stunning transformation and mostly thanks to the efforts and vision of the Compucorp Team. You can read a more in depth comparison to the UX evolution of other platforms like Salesforce and Blackbaud's Raisers Edge platform in the full in depth article here.