Very solid addon. The author has a well written description. It works well and can be customized.

Font size was a little small compared to what I'm currently using ('Tab Count Icon by lllusion3418'). It is very customizable (but 'Tab Counter Plus by Oriol Brufau' seemed to be slightly more so).

Personally, I will probably keep using TCI because the font size is very important to me (viewing from about 10ft away on a 50" TV set to 1920x1080 so every little bit helps) but I think many people would be happy with this as is.