It is fantastic for multi-agent systems. I have used multiple turtlebot 3 robots using ROS2 dashing and it is a real breeze to get them all up and running. I have even crated a guide on how to give them all different namespaces, which is the sort of challenge you may face if you decide to use turtlebots. Do be aware that the biggest limitation I have run into so far is device drivers for some hardware, but it isn’t too bad. Another is the lack of multi-robot launching from a single launch file. You will need to make launch files generic enough that they can be launched with a couple arguments from a bash script. There is ongoing work to update the launch command with remote machine launching capabilities, so keep an eye out for that.
A recent experiment of mine had multiple turtlebots sharing images with one another for topological mapping.