I've been using this extension for a month or so, and it does exactly what I want. I don't need anything fancy, just the ability to save my open tabs - usually across multiple, concurrent Firefox instances - when I have to reboot, so I can open them and resume work again quickly once I log back in. This extension does that easily and reliably, without otherwise getting in the way.

Note that I don't use bookmarks in Firefox, so the fact that this extension uses bookmarks to preserve sessions doesn't adversely impact me. Additionally, I wasn't a prior user of the apparently-famous Session Manager extension, so I have no expectations as to what an extension of this type should do. Taken on its own, MySessions does what it says it will do, in the way it says it will do it, and that fits my needs perfectly. Thanks to the developer for a job well-done!