With the new TLC the stego can easily become a must-tame early game dino for many players. It has 3 stances when ridden you can change between pressing C (crouch):
Heavy plate, boosting thatch gather rates and applying a heavy slow on hit targets.
Sharp plate, boosting berry gathering and attacks penetrate armour (useful for PvP).
Hardened plate, boosting wood gather and halves damage taken.
For combat, heavy plate is great for effectively rooting enemy and wild dinos in place, whilst hardened plate is to tank everything that comes at you. Sharpened plate shines together with allies that can slow and/or tank whilst you focus on dealing good dmg.
The alternate attack of the stego can impale creatures up to the size of roughly a parasaur, dealing damage based on attack damage. In order to do so the target must have a certain amount of health left, which is highlighted with the crosshair turning red when looking at the target (unsure how it is shown without crosshairs).