Halo was DoA for me after growing up with twitchy PC shooters like Unreal Tournament, Quake and Starsiege Tribes. The gameplay was glacially slow compared to what I was used to, but it did usher in online multiplayer to the console masses.
I really loved that about halo. The slower TTK makes for more chess like engagements, well with the exception of eating a shotty or a rocket to the face. Still, bouncing a perfect grenade or pulling off a ninja jump just feels so satisfying