The add-on is great and overall it works very well. You can customize the speech speed and pitch, stop, and rewind it. That said, it does have an issue on some linux distributions where it crashes the pulseaudio driver (but not all). It's not clear why this happens, but when it does the driver has to be restarted and then the plugin doesn't work again until a reboot. It's a bit of a niche problem so I only took off one star for it. That said, I put in a bug report for it and have heard nothing back from the dev despite a patch being released after my bug report.