Encounters with him are just annoying because it comes after you way too much to deal 33 or so damage to your vehicle repeatedly. Then after repairing the truck in a little crevice that it couldn't get to it somehow teleported the truck into its mouth and attacked me. About 30 seconds later it attacked me again.

First encounter was terrifying cuz it came out of nowhere to attack me. The shadow leviathans have a similar problem. So encounters with him just wind up being annoying while you are trying to get to a destination. Every time the bastard jumps out of the ice you get thrown off your hover bike (multiple times if you get back on right afterwards). However, after getting it I realized that the ice worm is more annoying than anything. The ice worm had a load of potential and was quite terrifying the first time I encountered it due to not having the snowfox yet. The Chelicerate jump scared me the first time I encountered it but after that initial impact I just jumped out of my truck and scanned it like no big deal. All the leviathans sounds to me in this game are kind of generic and don't have that 'You know I really shouldn't be here right now let's go back to base' feel to it. What made the Reaper scary? Well the horrific screaming and the fact that sound was your best ally to averting them. Personal opinion and spoilers if you haven't met the three leviathans in game.

Reaper leviathan subnautica below zero