Rated 4 out of 5 stars

One add-on with "2 themes" I think is a bit of exaggeration here; it's just you can see differently styled icons with "use small icons" turned on (good feature by itself though).
That said, it's a low-profile, simple and stylish theme. No question on its excellent design and I highly recommend it.
However, it's not completely achieved perfection in functionality yet; for instance, you can hardly tell whether a page is loading or not, just by seeing a tab.