I love that I can just drop it right onto my bookmarks bar! At a glance time for minimal real estate.
Clicking it cycles through various colours and between 12/24 hr formats.

It gets 5/5 stars for fulling its mission statement wonderfully well.
I would personally love an option to set a background colour also, and maybe make the time a display standard, rather than its 2 tiered (space saving) default.