* Super simpe, I like it
* Nice colorful icon easy to spot
suggestions
* save all tabs by default, I honestly never even heard you could "select" tabs (ctrl click) and never used it until I found out it wasnt working and tried ctrl clicking tabs before saving them. Even after learning it I think it's a hassle for me to do that extra step. Logically speaking a session is all the tabs, I don't see how selecting tabs to save is the main use case but maybe I'm the odd one.
* Some way to replace tabs instead of opening a window. I like to keep my window centered, and unfortunately a new window is always shifted from the default position, and then if I close that one last, my windows never open in the same spot. Maybe a checkbox " replace tabs in active window" (or some general setting that won't need to be in the popup)