I've been eating gelato pretty regularly across 3 weeks in Italy, and I've noticed that the top two gelato places I've been to (Grom in Florence and Hedera in Rome) both lack the "showiness" of other gelaterias -- no mounds of gelato here. They are hidden in proper freeze in silver canisters below the surface.
I also happen to be vegan, so my personal experience is based on the sorbetti (typically fruit flavors) and the granite (which is a softer version of sorbetto/gelato)
I liked this place so much I stopped by every day I was in Rome. Vegan/fruit flavor options in June included Fichi (fig), Limone (lemon), Fragola (strawberry), Melone (cantaloupe), Pesca (peach). I tried them all over the course of a few days and think the Fichi really shines. The others are wonderful too -- tastes like real fruit (because it includes it!).
They had 4 granite options (which are vegan) while I was there: caffe, fragola, mandorla (almond) and Limone (I think). If you're vegan, make sure to tell them you want it "senza latte" (without milk) so they don't add whipped cream or any vanilla gelato around it (as is apparently the current fashion with granite). I should also mention that this is not the slushy-style granite you see churning in almost every stall. It's very flavorful and almost like a thin ice cream.
On top of detour-worthy gelato/sorbetto/granite (my non-vegan family members attest to this), Ferdinando (the older gentleman) and Giuseppi (the younger man) are super friendly. When I stopped by to ask how late they were open on the first night, they remembered me when I came back. By the third day I felt like I would be cheating on their gelateria to try another place (but I have -- gotta make sure it's a fair review!)
Bottom line: Go here! If you're by the Vatican, you have no excuse to skip it. And if you haven't had gelato from the silver canisters before, you haven't tasted gelato yet.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.