I added Uruk'hai of Tolkien notoriety to my world some time ago. I have been generally happy with them, but I made them too powerful so I have been looking them over in general from the book to the movies by Peter Jackson and comparing them to humanoids in general in 1E, Orcs in particular.
Orcs are a one hit dice monster in 1E. I have little problem with that as in general, men and demi humans are also one hit dice at base as well. Men typically have 1d6 whereas demi-humans and humanoids use a d8. They are all about the same level in general.
PC's are the exception to the rule. They are able to accumulate much more hit points than the generic human, demi-human or humanoid as they gain new levels.
However, Uruk'hai are not your typical humanoid. They are created magically and with malicious intent for the purpose of killing. They are made of sterner stuff than your average Orc. Having said that, it's very tempting to want to overpower Uruk'hai in comparison to Orcs by giving them multiple hit dice.
That throws everything off though. Instead, what I have found that is working better was to downscale the Uruk'hai to being a 1 hd monster. The guaranteed 3 HP wil lset them up as being tougher than your average Orc, yet still not throwing things completely out of whack.
I gave Uruk'hai leaders 1+3 and commanders are 2+3 HD. This, to me, shows that the toughest Uruk'hai are the ones who take charge and have beaten most of the others as well as have demonstrated greater toughness on the battlefield.
I think of the scene in the Peter Jackson movie "The Fellowship of the Ring" when Uruk'hai are attacking Boromir and the rest in an effort to kidnap Frodo and recover the ring. Most of the attacking Uruk'hai seem to go down relatively easily at the hands of Aragorn and the others with the exception of the Uruk'hai commander with the bow. After shooting Boromir three times then being attacked from behind and stabbed then impaled by Aragorn, that Uruk'hai still has enough fortitude in him to pull himself forward on the sword to get closer to Aragorn. Clearly this Uruk'hai is not a 1 HD creature. It took being decapitated to stop him.
Uruk'hai will not stop, they have no fear so no need for a morale check. They will take no prisoners unless the one controlling them tells them to and then, they will just grab and go. There are no meaningful negotiations to be had with them.
There have been arguments about Orcs in the game and if they are inherently Evil or otherwise. This question doesn't even exist for Uruk'hai. They are made Evil. Their purpose is to kill and subdue everything else around them.
I like these monsters.