Farmer: Its the best early tame for berries, thatch, wood.
Fighter: Can kill everything smaller than rex-allosaurus with the knockback, so when you get trike the only fear is bronto (dont try fight bronto with it) . And much important, it is one of the few tames that dmg almost in every side of it, front-left-right and UP, doing it a decent fighter against birds too, if i could bring it on caves that no jump needed i wouldn't ask for another tame ever (killing bats)
The downside: its difficult to tame. 1) on hit and run he's gonna outrun you (and other trikes help him too), 2) On 'find a spot and throw him rocks (slingshot) seems good but after he got much torpidity it will run away fast on forest or sea and never see him again 3) Trapping him between wood walls-doorframes would work only if you play on 0-30 levels of creatures, in other case it will fck the wooden building immediately. And stone buildings are very far away when you start game
To sum up, no matter the difficulty of taming, its the best early game you gonna get and i mean it.