@Mr. Khan
Yeah, Knuckles' adventure was quite different from Sonic's, although the Egg Robo that Knuckles fought instead of Dr. Robotnik was always a little tougher than Sonic's boss battles. Still, that final fight with Super Mecha Sonic was fantastic. Brilliant ending.
@ODC
I'd buy it... even though I already have Sonic Mega Collection.
@Diplomatic
@wfz
Ya know mister, I'm not counting Sonic 3 & Knuckles as a game, seeing as I had to connect Sonic & Knuckles to Sonic the Hedgehog 3 to actually play the entire Death Egg Saga. Yes, I recognize its supreme awesomeness and yes, it's the best "game" ever. But Sonic & Knuckles is the greatest single cartridge game ever.