The greatest advantage is its compactness. I obtained a clock that can always be checked without changing the size of the toolbar.
You can utilize more screen space by not having to keep the taskbar always visible. When the taskbar is movable, it's difficult to check the clock while using the browser in full-screen mode. However, with this feature, you can achieve it simply by moving the cursor to the toolbar.

Using the color picker helps to compensate for the small size. Made face light yellow, hour hand black, minute hand green and, dots brown made the clock easier to read. Just googled best contrasting colors. Considering color adjustment would recommend otherwise not.

時計をオリジナルにできるのがすごく気に入っています♪とてもいいですね！カラーはyellowgreenにし、オプションからCUSTOM…で、オリジナルに打ち込みました。★MM/D（ddd）H:mm

very good and useful

Easy to configure, handy to use. Donate to him if you like it!

Exactly what I was looking for!

This is a wonderful small clock! Great job with adding the ability to customize the display colors and the tooltip text!!

Is there any chance the clock could be made larger? It would be easier to see.

Now, that's a really nice design! All pure, real time colour picker, mouseover date, and, actually you can read this itzy bitzy teeny tiny bugger! arigato

Konni'chiwa! What about to add the World Time feature? I need one after the FF major update. Domo arigatou!

the different between the hour and minute marker/hand is quite hard to differentiate since it's very small to begin with. So maybe come up with a different design for the "hand" rather than just simple line?

at its current state, i'm using it with the "small-clock" addons, a small digital clock right beside it, so now it's redundant or rather just a visual aid.

Was fine until recently, when I noticed the time being displayed appeared to change to UTC instead of local.

No sure if Firefox or extension but I thought I should mention it.