I'm insterested on how challenging this is on tougher difficulties, anyone know?

I liked the first Halo and the thing that made it really great was the Legendary difficulty, really made the game shine. I also agree that Halo 2 was vastly inferior and overrated online and offline, then again I used to play the original Halo online on my Xbox through Gamespy Tunnel, so Halo online was nothing new to me at that time.