AutoCAD is a complete program for designing buildings, objects and just about anything else that requires precision in 2D or 3D. This makes it very complex for beginners although there is extensive documentation and a series of tutorials to get you started. Also bear in mind that AutoCAD system requirements charge a high cost on your computer.
AutoCAD is suitable for both 2D and 3D drawing and is incredibly versatile, allowing you to customize almost every aspect of the design process. The intuitive interface has been much improved in recent years and now makes it much easier to identify the different functions available. You can create and edit DWG files quickly and, now that AutoCAD is available on Mac, work across platforms too.
One thing that catches some users out is that you have to be careful when updating designs and plans because if you make a change in a design, AutoCAD does not automatically update related files. So, if you change a detail in the section of a building, you must also remember to manually change the plan.
The biggest barrier for many people however will be the cost. AutoCAD is one of the most expensive pieces of software you will ever purchase, but the complexity and power of it will more than justify the cost for most professionals.