Con Proprietary drivers are unsupported
Fedora does not support proprietary drivers, meaning that users may have problems with a lot of hardware when using Fedora. The software to make that kind of hardware work can be installed, but it can be done only through third-parties and it's not easy for the average user.
Con Updating to new release can be problematic
While there are a few tools on offer that will upgrade an old Fedora release to the newest, there can often be problems with these methods. Some that may not even crop up at first but will show later down the road. Being that upgrading can be an issue, it can be exacerbated by the fact that Fedora updates every six month, which means twice a year there is a risk of completely borking ones install.