What is surfing a fish and twin fin feel like?

Almost every time when I see a good surfer on the line up and I ask them what they are surfing. It's usually a fish with twin fin. Luckily the ones I met are super nice and polite. So friendly even when I'm on a longboard surfing badly and hogging their waves.
I'll most likely never be able to surf a fish. But what is it with fish and twin fins? I always see those surfers are amazing and splashes water around. Are they much harder to surf? They always say they have other surfboards but it's good for these soft shoulders breaks. What makes them so fun compared to a shortboard or funboard?
I'll most likely never be able to surf a fish. But what is it with fish and twin fins? I always see those surfers are amazing and splashes water around. Are they much harder to surf? They always say they have other surfboards but it's good for these soft shoulders breaks. What makes them so fun compared to a shortboard or funboard?