Thank you for your comment! It is definitely not too late to learn how to use GIS. There are a couple of differences between QGIS and ArcGIS that might be considered drawbacks by some. For one, ArcGIS generally has a larger suite of tools and scripts to choose from. To get the same functionality with QGIS on certain tasks like slope and hydrological analyses, you either have to install third-party plugins or use a complimentary program called Grass GIS.

QGIS also behaves and looks a little different stylistically, so if you are already familiar with Arc then it might take some relearning. One of the biggest drawbacks is that certain files such as Geodatabases are proprietary file types that can only be opened by ArcGIS. Unfortunately, some state and federal organizations provide their data exclusively in this format, making it necessary to first convert the file if you want to use it in QGIS.