Upsides: more secure (in X.org every client can read every other client's keystrokes, pointer position, and do screen grabs), generally smoother rendering, better support for mixed-DPI setups.
Current downsides: worse support for screen recording/sharing (e.g. not supported in Skype), a bug in the compositor (e.g. GNOME Mutter) can bring your whole session down, not-as-good NVIDIA support (also depending on the compositor).
I have been using Wayland for two years or so an wouldn't want to go back. I do miss wide screen sharing support, because I am working remotely and Skype is the primary means of communication.
Current downsides: worse support for screen recording/sharing (e.g. not supported in Skype), a bug in the compositor (e.g. GNOME Mutter) can bring your whole session down, not-as-good NVIDIA support (also depending on the compositor).
I have been using Wayland for two years or so an wouldn't want to go back. I do miss wide screen sharing support, because I am working remotely and Skype is the primary means of communication.