Moments like the one you described were cool at first, but they're essentially no different to every other encounter in the game. The only difference is you're taking down your "nemesis", but simply dying to an Uruk isn't enough to make me consider them anything but a hurdle in the way.
They behave too similar to other Uruks, their weaknesses are too easily exploitable and the information required to do so is too easily obtained. More importantly, they appear so frequently that it becomes an inconvenience, when it could've been a significant moment.
That being said, I appreciate the nemesis system and I'm looking forward to the next game, even if I've had enough of this one half way through.