Lots of good features, but one important thing it seems to be missing is a one-click "save and close all tabs" button (in the style of OneTab and others). I'd also prefer to have context menu options and/or text labels on the popup menu toolbar, as I don't find the icons that intuitive. It would be one of my favourite extensions if it weren't for those aspects.
** Update ** To give a little more information on the tab closure suggestion, I think the way OneTab does it is to save & close all tabs in the current window and leave the window open with a blank tab, although that aspect might actually be down to my browser settings. I tend to have just one Firefox window open at a time, but it could perhaps be configurable to choose whether it acts on all open windows or just the current one. This feature is a big thing for me in terms of how valuable the add-on is, as when my browser gets too cluttered or I need to break off and do something else, I'd like to be able to just quickly click to save everything and come back to a nice clean window, when I can then restore tabs one by one as I want to work on them. Nonetheless, on reflection I think maybe my original 3* rating was a little harsh, I've decided to make it 4*, but I think the addition of this save & close option would push it up to 5 for me, along with the labelling enhancement - good to hear that's planned. Just to emphasise, I think speed and ease of use is really important, so that when busy I can save or restore in one or two clicks without really having to switch between views or figure out which button to click.
Finally, one other thought is that some add-ons (e.g. TabStash) make use of the sidebar, and I like that as it provides instant access to sessions and reminds me what I have queued up as I can have it showing all the time. I realise that's probably quite a big thing to implement, but maybe worth considering? Thanks!
** Update 2 ** One other feature that would be very welcome would be a one-click option to remove an entry from a session when restoring/reopening it. So let's say I saved a session yesterday with sites A-F, and today I'm reopening sites A-C to work in them. Instead of having to click on each to restore and then go back to each and delete from the session, it would be nice to have an "Open and remove" option (which could perhaps be set as default left-click behaviour if preferred, maybe with a shift-to-override option too). Would be great if you'd consider adding this please! Thanks