The Bottle: I get the feeling that this hasn't changed much since its inception in 1845. It screams "classic Italian bitters". I have no idea what any of it says, but it looks good in the process.
In the Glass: Dark brown with the slightest halo of green around the edge of the liquid as you swirl it in the glass.
On the Nose: Bitter mint. Now, I know that sounds off-putting, but go with me on this one. It has a strong "mint of the earth" thing going for it. It isn't cloying like peppermint schnapps, nor is it as strikingly medicinal as something like Gammel Dansk. It strikes a nice balance.
Taste: I mean, it's a bitters. Chances are that you aren't drinking this on it's own. But, if you did, it would taste something like really artisanal toothpaste with a bitter kick in the teeth. If the Romans made toothpaste, this is what it would be like.
Fernet-Branca shines best in measured proportions in a number of cocktails, in my opinion. I know that a pour of it often shows up as a "bartender's handshake", but it takes an experienced palate to get the most out of this on its own. If you are getting started with this, I'd suggest the simple Coke & Fernet or a Toronto to a feel for how it can work best.